
The Florida Keys are a
coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
cay
A cay ( ), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic, and Indian oceans, including in the Caribbean and on the Grea ...
archipelago
An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...
off the southern coast of
Florida
Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida
peninsula
A peninsula is a landform that extends from a mainland and is only connected to land on one side. Peninsulas exist on each continent. The largest peninsula in the world is the Arabian Peninsula.
Etymology
The word ''peninsula'' derives , . T ...
, about south of
Miami
Miami is a East Coast of the United States, coastal city in the U.S. state of Florida and the county seat of Miami-Dade County, Florida, Miami-Dade County in South Florida. It is the core of the Miami metropolitan area, which, with a populat ...
and extend in an arc south-southwest and then westward to
Key West
Key West is an island in the Straits of Florida, at the southern end of the U.S. state of Florida. Together with all or parts of the separate islands of Dredgers Key, Fleming Key, Sunset Key, and the northern part of Stock Island, it con ...
, the westernmost of the inhabited islands, and on to the uninhabited
Dry Tortugas
Dry Tortugas National Park is a national park of the United States located about west of Key West in the Gulf of Mexico, in the United States. The park preserves Fort Jefferson and the several Dry Tortugas islands, the westernmost and most iso ...
. The islands lie along the
Florida Straits
The Straits of Florida, Florida Straits, or Florida Strait () is a strait located south-southeast of the North American mainland, generally accepted to be between the Gulf of Mexico and the Atlantic Ocean, and between the Florida Keys (U.S.) ...
, dividing the
Atlantic Ocean
The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
to the east from the
Gulf of Mexico
The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
to the northwest, and defining one edge of
Florida Bay
Florida Bay is the bay located between the southern end of the Florida mainland (the Everglades, Florida Everglades) and the Florida Keys in the United States. It is a large, shallow estuary that while connected to the Gulf of Mexico, has limited ...
. The southern part of Key West is from
Cuba
Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...
. The Keys are located between about 24.3 and 25.5 degrees North latitude.
More than 95% of the land area lies in
Monroe County, but a small portion extends northeast into
Miami-Dade County
Miami-Dade County () is a county located in the southeastern part of the U.S. state of Florida. The county had a population of 2,701,767 as of the 2020 census, making it the most populous county in Florida and the seventh-most-populous coun ...
, such as
Totten Key. The total land area is . At the
2010 census the population was 73,090, with an average density of ,
although much of the population is concentrated in a few areas of much higher density, such as the city of Key West, which has 32% of the Keys' total population. The 2014 Census population estimate was 77,136. The 2020 Census population estimate was 82,874.
The city of Key West is the
county seat
A county seat is an administrative center, seat of government, or capital city of a county or parish (administrative division), civil parish. The term is in use in five countries: Canada, China, Hungary, Romania, and the United States. An equiva ...
of Monroe County. The county consists of a section on the
mainland which is almost entirely in
Everglades National Park
Everglades National Park is a List of national parks of the United States, national park of the United States that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the Un ...
, and the Keys islands from
Key Largo to
Dry Tortugas National Park
Dry Tortugas National Park is a national park of the United States located about west of Key West in the Gulf of Mexico, in the United States. The park preserves Fort Jefferson and the several Dry Tortugas islands, the westernmost and most iso ...
.
History
The Keys were originally inhabited by the
Calusa
The Calusa ( , Calusa: *ka(ra)luś(i)) were a Native American people of Florida's southwest coast. Calusa society developed from that of archaic peoples of the Everglades region. Previous Indigenous cultures had lived in the area for thousands o ...
and
Tequesta
The Tequesta, also Tekesta, Tegesta, Chequesta, Vizcaynos, were a Native American tribe on the Southeastern Atlantic coast of Florida. They had infrequent contact with Europeans and had largely migrated by the middle of the 18th century.
Loca ...
people and were later charted by
Juan Ponce de León
Juan Ponce de León ( – July 1521) was a Spanish explorer and ''conquistador'' known for leading the first official European expedition to Puerto Rico in 1508 and Florida in 1513. He was born in Santervás de Campos, Valladolid, Spain, in ...
in 1513. De León named the islands ''Los Martires'' ("The Martyrs"), as they looked like suffering men from a distance. "Key" is derived from the Spanish word ''cayo'', meaning small island. For many years, Key West was the largest town in Florida, and it grew prosperous on
wrecking revenues. The isolated outpost was well located for trade with Cuba and the Bahamas and was on the main trade route from
New Orleans
New Orleans (commonly known as NOLA or The Big Easy among other nicknames) is a Consolidated city-county, consolidated city-parish located along the Mississippi River in the U.S. state of Louisiana. With a population of 383,997 at the 2020 ...
. Improved navigation led to fewer shipwrecks, and Key West went into a decline in the late nineteenth century.
Overseas Railway
The Keys were long accessible only by water. This changed with the completion of
Henry Flagler
Henry Morrison Flagler (January 2, 1830 – May 20, 1913) was an American industrialist and a founder of Standard Oil, which was first based in Ohio. He was also a key figure in the development of the Atlantic coast of Florida and founder ...
's
Overseas Railway in the early 1910s. Flagler, a major developer of Florida's Atlantic coast, extended his
Florida East Coast Railway
The Florida East Coast Railway is a Class II railroad operating in the U.S. state of Florida, currently owned by Grupo México.
Built primarily in the last quarter of the 19th century and the first decade of the 20th century, the FEC was a p ...
down to Key West with an ambitious series of oversea railroad trestles. Three hurricanes disrupted the project in
1906
Events
January–February
* January 12 – Persian Constitutional Revolution: A nationalistic coalition of merchants, religious leaders and intellectuals in Persia forces the shah Mozaffar ad-Din Shah Qajar to grant a constitution, ...
,
1909, and
1910
Events
January
* January 6 – Abé people in the French West Africa colony of Côte d'Ivoire rise against the colonial administration; the rebellion is brutally suppressed by the military.
* January 8 – By the Treaty of Punakha, t ...
.
1935 Labor Day hurricane
The strongest hurricane to strike the U.S. made landfall near Islamorada in the Upper Keys on Labor Day, Monday, September 2, 1935. Winds were estimated to have gusted to , raising a storm surge more than above sea level that washed over the islands. More than 400 people were killed, though some estimates place the number of deaths at more than 600.
The Labor Day hurricane was one of only four hurricanes to make landfall at
Category 5 strength on the U.S. coast since reliable weather records began (about 1850). The other storms were
Hurricane Camille
Hurricane Camille was a powerful, deadly and destructive tropical cyclone which became the second most intense on record to strike the United States (behind the 1935 Labor Day hurricane) and is one of the four Category 5 hurricanes to make ...
(1969),
Hurricane Andrew
Hurricane Andrew was a compact, but very powerful and devastating tropical cyclone that struck the Bahamas, Florida, and Louisiana in August 1992. It was the most destructive hurricane to ever hit Florida in terms of structures dama ...
(1992), and
Hurricane Michael (2018).
In 1935, new bridges were under construction to connect a highway through the entire Keys. Hundreds of World War I veterans working on the roadway as part of a government relief program were housed in non-reinforced buildings in three construction camps in the Upper Keys. When the evacuation train failed to reach the camps before the storm, more than 200 veterans perished. Their deaths caused anger and charges of mismanagement that led to a Congressional investigation.
The storm also ended the 23-year run of the Overseas Railway; the damaged tracks were never rebuilt, and the
Overseas Highway
The Overseas Highway is a highway carrying U.S. Route 1 (US 1) through the Florida Keys to Key West. Large parts of it were built on the former right-of-way of the Overseas Railroad, the Key West Extension of the Florida East Coast Ra ...
(
U.S. Highway 1) replaced the railroad as the main transportation route from Miami to Key West.
Seven Mile Bridge
One of the
longest bridges when it was built, the
Seven Mile Bridge connects
Knight's Key (part of the city of
Marathon
The marathon is a long-distance foot race with a distance of kilometres ( 26 mi 385 yd), usually run as a road race, but the distance can be covered on trail routes. The marathon can be completed by running or with a run/walk strategy. There ...
in the Middle Keys) to
Little Duck Key in the Lower Keys. The piling-supported concrete bridge is or 6.79 miles (10.93 km) long. The current bridge bypasses
Pigeon Key, a small island that housed workers building
Henry Flagler
Henry Morrison Flagler (January 2, 1830 – May 20, 1913) was an American industrialist and a founder of Standard Oil, which was first based in Ohio. He was also a key figure in the development of the Atlantic coast of Florida and founder ...
's
Florida East Coast Railway
The Florida East Coast Railway is a Class II railroad operating in the U.S. state of Florida, currently owned by Grupo México.
Built primarily in the last quarter of the 19th century and the first decade of the 20th century, the FEC was a p ...
in the 1900s, that the original Seven Mile Bridge crossed. A section of the old bridge remains for access to the island, although it was closed to vehicular traffic on March 4, 2008. The aging structure has been deemed unsafe by the
Florida Department of Transportation
The Florida Department of Transportation (FDOT) is a decentralized agency charged with the establishment, maintenance, and regulation of public transportation in the U.S. state of Florida. The department was formed in 1969. It absorbed the power ...
. Costly repairs, estimated to be as much as $34 million, were expected to begin in July 2008. Monroe County was unable to secure a $17 million loan through the state infrastructure bank, delaying work for at least a year. On June 14, 2008, the old bridge section leading to Pigeon Key was closed to fishing as well. While still open to pedestrians—walking, biking and jogging—if the bridge were closed altogether, only a ferry subsidized by FDOT and managed by the county would transport visitors to the island.
Overseas Highway
After the destruction of the Keys railway by the
Labor Day Hurricane of 1935, the railroad bridges, including the Seven Mile Bridge, were converted to automobile roadways. This roadway, U.S. Highway 1, became the
Overseas Highway
The Overseas Highway is a highway carrying U.S. Route 1 (US 1) through the Florida Keys to Key West. Large parts of it were built on the former right-of-way of the Overseas Railroad, the Key West Extension of the Florida East Coast Ra ...
that runs from Key Largo south to Key West. Today this highway allows travel through the tropical islands of the Florida Keys and the viewing of exotic plants and animals found nowhere else on the US mainland and the largest
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...
chain in the United States.
Cuban exiles
Following the
Cuban Revolution
The Cuban Revolution () was the military and political movement that overthrew the dictatorship of Fulgencio Batista, who had ruled Cuba from 1952 to 1959. The revolution began after the 1952 Cuban coup d'état, in which Batista overthrew ...
, many Cubans emigrated to South Florida. Key West traditionally had strong links with its neighbor ninety miles south by water, and large numbers of Cubans settled there. The Keys still attract Cubans leaving their home country, and stories of "rafters" coming ashore are not uncommon.
Conch Republic
In 1982, the
United States Border Patrol
The United States Border Patrol (USBP) is a Federal law enforcement in the United States, federal law enforcement agency under the U.S. Customs and Border Protection, United States Customs and Border Protection (CBP) and is responsible for secu ...
established a roadblock and inspection points on
US Highway 1, stopping all northbound traffic returning to the mainland at
Florida City, to search vehicles for illegal drugs and undocumented immigrants. The Key West City Council repeatedly complained about the roadblocks, which were a major inconvenience for travellers, and hurt the Keys' important tourism industry.
After various unsuccessful complaints and attempts to get a legal injunction against the blockade failed in federal court in
Miami
Miami is a East Coast of the United States, coastal city in the U.S. state of Florida and the county seat of Miami-Dade County, Florida, Miami-Dade County in South Florida. It is the core of the Miami metropolitan area, which, with a populat ...
, on April 23, 1982, Key West mayor
Dennis Wardlow and the city council declared the independence of the city of
Key West
Key West is an island in the Straits of Florida, at the southern end of the U.S. state of Florida. Together with all or parts of the separate islands of Dredgers Key, Fleming Key, Sunset Key, and the northern part of Stock Island, it con ...
, calling it the "
Conch Republic", and declared war on the United States by striking an officer of the Key West Naval Air Station (NAS) on the head with a loaf of stale Cuban bread. After one minute of secession, he (as "Prime Minister") surrendered to the officer and requested US$1,000,000,000 in "
foreign aid
In international relations, aid (also known as international aid, overseas aid, foreign aid, economic aid or foreign assistance) is – from the perspective of governments – a voluntary transfer of resources from one country to another. The ...
".
The stunt succeeded in generating great publicity for the Keys' plight, and the inspection station roadblock was removed. The idea of the Conch Republic has provided a new source of revenue for the Keys by way of tourist keepsake sales, and the Conch Republic has participated in later protests.
Geology
The northern and central sections of the Florida Keys are the exposed portions of an ancient
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...
, the
Key Largo Limestone
The Key Largo Limestone is a Formation (stratigraphy), geologic formation in Florida. It is a fossilized coral reef. The formation is exposed along the upper and middle Florida Keys from Soldier Key (at the north end of the Florida Keys) to the ...
. The northernmost island arising from the ancient reef formation is
Elliott Key, in
Biscayne National Park. North of Elliott Key are several small transitional keys, composed of sand built up around small areas of exposed ancient reef. Further north,
Key Biscayne
Key Biscayne () is an island located in Miami-Dade County, Florida, located between the Atlantic Ocean and Biscayne Bay. It is the southernmost of the barrier islands along the Atlantic coast of Florida, and lies south of Miami Beach and sout ...
and places north are
barrier island
Barrier islands are a Coast#Landforms, coastal landform, a type of dune, dune system and sand island, where an area of sand has been formed by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of an ...
s, built up of sand. The islands in the southwestern part of the chain, from
Big Pine Key to the
Marquesas Keys, are exposed areas of
Miami Limestone
The Miami Limestone, originally called Miami Oolite, is a Formation (stratigraphy), geologic formation of limestone in southeastern Florida.
Miami Limestone forms the Atlantic Coastal Ridge in southeastern Florida, near the coast in Palm Beach ...
.
The Florida Keys have taken their present form as the result of the drastic changes in sea level associated with recent
glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
s or ''
ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...
s''. Beginning some 130,000 years ago the
Sangamonian Stage raised sea levels about above the current level. All of southern Florida was covered by a shallow sea. Several parallel lines of reef formed along the edge of the submerged
Florida Platform, stretching south and then west from the present Miami area to what is now the Dry Tortugas. This reef formed the Key Largo Limestone that is exposed on the surface from
Soldier Key (midway between Key Biscayne and Elliott Key) to the southeast portion of
Big Pine Key and the Newfound Harbor Keys. The types of
coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
that formed Key Largo Limestone can be identified on the exposed surface of these keys. Minor fluctuations in sea level exposed parts of the reef, subjecting it to erosion. Acidic water, which can result from decaying vegetation, dissolves limestone. Some of the dissolved limestone redeposited as a denser ''cap rock'', which can be seen as outcrops overlying the Key Largo and Miami limestones throughout the Keys. The limestone that eroded from the reef formed
oolite
Oolite or oölite () is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pis ...
s in the shallow sea behind the reef, and together with the skeletal remains of
bryozoans, formed the Miami Limestone that is the current surface bedrock of the lower Florida peninsula and the lower keys from Big Pine Key to Key West. To the west of Key West the ancient reef is covered by recent
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines.
In zoology
''Calcare ...
sand. While the islands of the upper and middle keys, consisting of Key Largo Limestone, form a long narrow arc, the islands of the lower keys are perpendicular to the line of that arc. This configuration arose from an ancient tidal-bar system, in which
tidal channels cut through a submerged oolitic deposit. The bars
lithified
Lithification (from the Ancient Greek word ''lithos'' meaning 'rock' and the Latin-derived suffix ''-ific'') is the process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially, lithificati ...
into Miami Limestone, and with changes in sea level are presently exposed as the islands, while the channels between the bars now separate the islands.
Just offshore of the Florida Keys along the edge of the Florida Straits is the
Florida Reef (also known as the Florida Reef Tract), separated from the keys by the
Hawk Channel. The Florida Reef extends from
Fowey Rocks just east of Soldier Key to just south of the Marquesas Keys. It is the third-largest
barrier reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
C ...
system in the world.
Environment

The climate and environment of the Florida Keys are closer to that of the
Caribbean
The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
than the rest of Florida, though unlike the Caribbean's volcanic islands, the Keys were built by plants and animals. The Upper Keys islands are composed of sandy-type accumulations of
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
grains produced by plants and marine organisms. The Lower Keys are the remnants of large coral reefs, which became fossilized and exposed when the sea level dropped.
The natural habitats of the Keys are upland forests, inland wetlands and shoreline zones. Soil ranges from sand to
marl
Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae.
M ...
to rich, decomposed
leaf litter
Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
. In some places, "caprock" (the eroded surface of coral formations) covers the ground. Rain falling through
leaf debris becomes acidic and dissolves holes in the limestone, where soil accumulates and trees root.
Flora and fauna

The Florida Keys have distinctive plant and animals species, some found nowhere else in the United States, as the Keys define the northern extent of their ranges. The climate also allows many imported plants to thrive. Some exotic species which arrived as landscape plants now invade and threaten natural areas.
The native flora of the Keys is diverse, including members of both temperate families, such as red maple (''
Acer rubrum
''Acer rubrum'', the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest Service recognizes it as the most abundant nati ...
''), slash pine (
''Pinus elliottii'' var. ''densa'') and oaks (''
Quercus
An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
'' spp.), growing at the southern end of their ranges, and tropical families, including mahogany (''
Swietenia mahagoni
''Swietenia mahagoni'', commonly known as American mahogany, Cuban mahogany, small-leaved mahogany, and West Indian mahogany, is a species of ''Swietenia'' native to the broader Caribbean bioregion. It is the species from which the original mahog ...
''), gumbo limbo (''
Bursera simaruba
''Bursera simaruba'', commonly known as gumbo-limbo, the tourist tree, copperwood, almácigo, chaca, West Indian birch, naked Indian, and turpentine tree, is a tree species in the family Burseraceae, native to the Neotropics, from South Florid ...
''), stoppers (''
Eugenia'' spp.), Jamaican dogwood (''
Piscidia piscipula''), and many others, which grow only in tropical climates. Several types of palms are native to the Florida Keys, including the Florida thatch palm (''
Thrinax radiata''), which grows to its greatest size in Florida on the islands of the Keys.
The Keys are also home to unique animal species, including the
American crocodile
The American crocodile (''Crocodylus acutus'') is a species of crocodilian found in the Neotropics. It is the most widespread of the four Extant taxon, extant species of crocodiles from the Americas, with populations present from South Florida, ...
,
Key deer
The Key deer (''Odocoileus virginianus clavium'') is an endangered subspecies of the white-tailed deer that lives only in the Florida Keys. It is the smallest extant North American deer species.
Description
This deer can be recognized by its ch ...
(protected by the
National Key Deer Refuge), and the
Key Largo woodrat. The Keys are part of the northernmost range of the American crocodile, which is found throughout the
Neotropics
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
Definition
In biogeog ...
. The Key Largo Woodrat is found only in the northern part of its namesake island and is a focus of management activities in
Crocodile Lake National Wildlife Refuge. About 70 miles (110 km) west of Key West is
Dry Tortugas National Park
Dry Tortugas National Park is a national park of the United States located about west of Key West in the Gulf of Mexico, in the United States. The park preserves Fort Jefferson and the several Dry Tortugas islands, the westernmost and most iso ...
.
The waters surrounding the Keys are part of a protected area known as the
Florida Keys National Marine Sanctuary.
Climate
The climate of the Florida Keys is
tropical savanna (
Köppen climate classification
The Köppen climate classification divides Earth climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (te ...
: Aw). Other than some areas of coastal Miami (Miami Beach), the Florida Keys are the only areas in the continental United States to never report freezing temperatures since settlement. The record low in Key West is (in both 1886 and 1981), and low temperatures below are rare. Most of the Florida Keys fall into USDA zone 11a to 11b; Key West is zone 12a.
There are two main "seasons" in the Florida Keys, a hot and wet season from June through October, and a dry season from November through April, that features little rainfall, sunny skies, and warm breezy conditions. The warm and sunny winter climate, with average highs around and lows above , is the main tourist season in the Florida Keys. Key West is the driest city in Florida, and most of the Florida Keys can become quite dry at the height of the dry season. Some of the more exposed vegetation in the keys is
scrub, stunted due to the intense sun, quick draining sandy soil, and arid winter climate.
Tropical cyclones

The Keys are occasionally threatened by
tropical storm
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its lo ...
s and
hurricane
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its ...
s, leading to evacuations to the mainland.
Hurricane Georges, after destroying much of the housing and infrastructure on many of the
Caribbean islands
Most of the Caribbean countries are islands in the Caribbean Sea, with only a few in inland lakes. The largest islands include Cuba, Hispaniola, Jamaica and Puerto Rico. Some of the smaller islands are referred to as a ''rock'' or ''reef.''
''I ...
, caused damage and extensive flooding in the Lower Keys in 1998, before making
landfall
Landfall is the event of a storm moving over land after being over water. More broadly, and in relation to human travel, it refers to 'the first land that is reached or seen at the end of a journey across the sea or through the air, or the fact ...
in
Mississippi
Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...
. In 2005, Hurricanes
Katrina,
Rita and
Wilma affected the Keys (although none made a direct hit), causing widespread damage and flooding. The most severe hurricane to hit the area was the
Labor Day Hurricane of 1935, a Category 5 hurricane.
Tropical cyclones present special dangers and challenges to the entire Keys. Because no area of the islands is more than above sea level (and many are only a few feet elevation), and water surrounds the islands, nearly every neighborhood is subject to flooding as well as hurricane winds. In response, many homes in the Keys are built on concrete stilts with the first floor being not legally habitable and enclosed by breakaway walls that are not strongly attached to the rest of the house. Nonetheless, Monroe County, as reported in the Federal Register, has estimated that there are between 8,000 and 12,000 illegal enclosures inhabited by people.
Because of the threat from storm surge, evacuations are routinely ordered when the
National Weather Service
The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...
issues a hurricane watch or warning, and are sometimes ordered for a tropical storm warning. Evacuation of the Keys depends on causeways and the two-lane highway to the mainland. Time estimates for evacuating the entire Keys range from 12 to 24 hours. Evacuation estimates are significant in emergency planning, of course, but also because they are a factor in local and state regulations for controlling development. The building permit allocation was increased in 2005 when local governments reduced estimates for evacuation.
On September 10, 2017,
Hurricane Irma
Hurricane Irma was an extremely powerful and devastating tropical cyclone that was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Hurricane Maria, Maria two weeks later. At the time, it was considered ...
made landfall in Cudjoe Key. The storm destroyed an estimated 25% of the houses on the Keys and another 65% suffered major damage. Most residents had evacuated before the storm hit the area. On September 12, parts of the Keys were still inaccessible by causeway and some areas were closed to the public. Governor
Rick Scott
Richard Lynn Scott ( Myers; born December 1, 1952) is an American attorney, businessman, politician, and United States Navy, Navy veteran serving as the Seniority in the United States Senate, senior United States senator from the state of F ...
reported devastation; most areas were without power or water. The damage was the worst in the Lower Keys, though less severe in Key West; parts of the Lower Keys may be uninhabitable for months.
Major islands
U.S. Highway 1, the "
Overseas Highway
The Overseas Highway is a highway carrying U.S. Route 1 (US 1) through the Florida Keys to Key West. Large parts of it were built on the former right-of-way of the Overseas Railroad, the Key West Extension of the Florida East Coast Ra ...
", runs over most of the inhabited islands of the Florida Keys. The islands are listed in order from southwest to north.
Mile markers are listed for keys that the Overseas Highway runs across or near:
[FDOT straight line diagrams]
, accessed April 2014.
*
Dry Tortugas
Dry Tortugas National Park is a national park of the United States located about west of Key West in the Gulf of Mexico, in the United States. The park preserves Fort Jefferson and the several Dry Tortugas islands, the westernmost and most iso ...
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Loggerhead Key
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Marquesas Keys
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Sunset Key
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Wisteria Island
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Key West
Key West is an island in the Straits of Florida, at the southern end of the U.S. state of Florida. Together with all or parts of the separate islands of Dredgers Key, Fleming Key, Sunset Key, and the northern part of Stock Island, it con ...
(MM 0–4)
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Fleming Key
Fleming Key is an island off the northwest corner of the island of Key West, Florida in the lower Florida Keys
The Florida Keys are a coral island, coral cay archipelago off the southern coast of Florida, forming the southernmost part of th ...
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Sigsbee Park
Sigsbee Park, also known as ''Dredgers Key'', is an island about half a mile (800 m) north of Key West island in the lower Florida Keys; administratively it is within the City of Key West, Florida, United States.
It is connected to the isl ...
(off to the north at MM 2¾)
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Stock Island (MM 5)
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Raccoon Key (off to the north at MM 5¼)
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Boca Chica Key (MM 7–8)
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Rockland Key (MM 9)
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East Rockland Key (MM 9½)
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Big Coppitt Key (MM 10)
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Geiger Key (off to the south at MM 10¾)
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Shark Key (off to the north at MM 11¼)
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Saddlebunch Keys (MM 12–16)
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Lower Sugarloaf Key (MM 17)
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Park Key (MM 18)
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Sugarloaf Key
Sugarloaf Key is a single island in the lower Florida Keys that forms a loop on the Atlantic Ocean side, giving the illusion of separate islands. Although frequently referred to simply and with technical accuracy as "Sugarloaf Key", this island ...
(MM 19–20)
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Cudjoe Key (MM 21–23)
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Knockemdown Key
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Summerland Key (MM 24–25)
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Ramrod Key (MM 27)
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Middle Torch Key,
Big Torch Key (off to the north at MM 27¾)
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Little Torch Key (MM 28½)
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Big Pine Key (MM 30–32)
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No Name Key
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Scout Key (MM 34–35), formerly known as West Summerland Key
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Bahia Honda Key (MM 37–38)
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Ohio Key
U.S. Route 1 in Florida, US 1 (or the Overseas Highway) crosses the Ohio Key at approximately mile marker 39, between Missouri Key and Bahia Honda Key. Today it is also known as Sunshine Key, after a camping resort located there. The portion of t ...
(MM 38¾), also known as Sunshine Key
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Missouri Key (MM 39¼)
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Little Duck Key (MM 39¾)
The
Seven Mile Bridge (MM 40–46¾) separates the Lower Keys from the Middle Keys:
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Pigeon Key (off to the north near MM 45; access is at MM 46¾)
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Knights Key (MM 47)
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Vaca Key (MM 48–53)
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Boot Key (off to the south at MM 48; bridge closed)
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Fat Deer Key (MM 53¼-55)
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Shelter Key (off to the south at MM 53¾)
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Long Point Key (MM 56)
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Crawl Key (MM 56½)
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Grassy Key (MM 58–60)
(Knights, Vaca, Boot, Long Point, Crawl, and Grassy Keys, as well as most of Fat Deer Key, are incorporated in the city of
Marathon
The marathon is a long-distance foot race with a distance of kilometres ( 26 mi 385 yd), usually run as a road race, but the distance can be covered on trail routes. The marathon can be completed by running or with a run/walk strategy. There ...
. The remaining portion of Fat Deer Key and most of Shelter Key are part of
Key Colony Beach.):
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Duck Key (MM 61)
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Conch Key (MM 62–63)
The
Long Key Bridge (MM 63¼-65¼) separates the Middle Keys from the Upper Keys:
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Long Key (MM 66–70), formerly known as Rattlesnake Key
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Fiesta Key (off to the north at MM 70)
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Craig Key (MM 72)
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Lower Matecumbe Key (MM 74–77)
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Lignumvitae Key
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Indian Key
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Indian Key Fill (MM 79)
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Tea Table (MM 79½)
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Upper Matecumbe Key (MM 80–83)
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Windley Key (MM 85)
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Plantation Key (MM 86–90)
(Lower Matecumbe through Plantation Keys are incorporated as
Islamorada, Village of Islands. The "towns" of
Key Largo,
North Key Largo and
Tavernier, all on the island of Key Largo, are not incorporated.):
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Key Largo (MM 91–107)
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Tavernier Key
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Rodriguez Key
All keys north of
Broad Creek are in
Biscayne National Park and
Miami-Dade County
Miami-Dade County () is a county located in the southeastern part of the U.S. state of Florida. The county had a population of 2,701,767 as of the 2020 census, making it the most populous county in Florida and the seventh-most-populous coun ...
. The following are "true" Florida Keys (exposed ancient coral reefs):
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Old Rhodes Key
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Totten Key
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Reid Key
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Rubicon Keys
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Adams Key
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Elliott Key
The following are "transitional keys", made of exposed ancient reef surrounded by sand:
*
Sands Key
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Boca Chita Key
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Ragged Keys
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Soldier Key
Key Biscayne
Key Biscayne () is an island located in Miami-Dade County, Florida, located between the Atlantic Ocean and Biscayne Bay. It is the southernmost of the barrier islands along the Atlantic coast of Florida, and lies south of Miami Beach and sout ...
is not one of the Florida Keys, but the southernmost of the
barrier island
Barrier islands are a Coast#Landforms, coastal landform, a type of dune, dune system and sand island, where an area of sand has been formed by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of an ...
s along the Atlantic coast of Florida.
Transportation
The main chain of Keys islands can be traveled by motor vehicles on the
Overseas Highway
The Overseas Highway is a highway carrying U.S. Route 1 (US 1) through the Florida Keys to Key West. Large parts of it were built on the former right-of-way of the Overseas Railroad, the Key West Extension of the Florida East Coast Ra ...
, a section of
U.S. 1, which runs from Key West to
Fort Kent, Maine
Fort Kent ( French: ''Fort-Kent'') is a town in Aroostook County, Maine, United States, situated at the confluence of the Fish River and the Saint John River, on the border with New Brunswick, Canada. The population was 4,067 in the 2020 cens ...
in its entirety. The highway was built parallel to the original route of the
Overseas Railway, which was not rebuilt following the
Labor Day hurricane of 1935. Even before the hurricane, road sections and highway bridges allowed automobile traffic to travel from Miami to Lower Matecumbe Key, where a car ferry connected with another roadway section through the Lower Keys. Following the hurricane, some of the original railway bridges were converted to carry the highway roadbeds. These bridges were used until the 1980s, when new highway bridges were built alongside. Many of the original railroad and highway bridges remain today as pedestrian fishing piers.
Public transportation

The Florida Keys has public bus transportation.
Road hazards
Despite this reconstruction, U.S. 1 was not widened on a large scale, and today most of the route consists of just two lanes. Due to their tropical climate, the Florida Keys attract several hundred thousand tourists annually. While some visitors arrive via
Key West International Airport and
Florida Keys Marathon Airport in
Marathon
The marathon is a long-distance foot race with a distance of kilometres ( 26 mi 385 yd), usually run as a road race, but the distance can be covered on trail routes. The marathon can be completed by running or with a run/walk strategy. There ...
, cruise ship or ferry from
Miami
Miami is a East Coast of the United States, coastal city in the U.S. state of Florida and the county seat of Miami-Dade County, Florida, Miami-Dade County in South Florida. It is the core of the Miami metropolitan area, which, with a populat ...
,
Fort Myers
A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Lati ...
, or Marco Island, Florida, the vast majority of tourists drive down from the mainland on U.S. 1. This influx of traffic, coupled with the two-lane nature of U.S. 1 through most of its length in the Keys, and the fact that no alternative road routes are available mean that Monroe County has the highest
per capita
''Per capita'' is a Latin phrase literally meaning "by heads" or "for each head", and idiomatically used to mean "per person".
Social statistics
The term is used in a wide variety of social science, social sciences and statistical research conte ...
rate of fatal
automobile accidents in the state of Florida.
Culture and recreation
The major industries are fishing and tourism, including
ecotourism
Ecotourism is a form of nature-oriented tourism intended to contribute to the Ecological conservation, conservation of the natural environment, generally defined as being minimally impactful, and including providing both contributions to conserv ...
, with many visitors
scuba diving
Scuba diving is a Diving mode, mode of underwater diving whereby divers use Scuba set, breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The word ''scub ...
in the area's protected waters. A ferry takes riders between Key West and
Fort Myers
A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Lati ...
, as well as
Marco Island
Marco may refer to:
People Given name
* Marco (actor) (born 1977), South Korean model and actor
Surname
* Georg Marco (1863–1923), Romanian chess player of German origin
* Jindřich Marco (1921–2000), Czechoslovak photographer and numismat ...
due north on the mainland, along the western edge of Florida Bay.
Dark skies recreation

Middle and Lower Florida Keys are among a few remaining South Florida dark skies locations accessible by car, thanks to their position along the Atlantic Ocean, and therefore with southern skies unobstructed by
light pollution
Light pollution is the presence of any unwanted, inappropriate, or excessive artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting sources, during the ...
associated with urban development.
Scout Key is home to
Winter Star Party
The Winter Star Party, aka WSP, is an annual convention of amateur astronomers where the primary activity is nighttime astronomical observation. This February event is run at Camp Wesumkee located on Scout Key in the Lower Florida Keys. It is host ...
, a prominent annual amateur astronomy event in the United States, and one of the Top 10 star parties in the world according to
BBC Sky at Night. It is an international gathering that attracts 500+ people each year who enjoy stargazing, astrophotography and Milky Way photography.
Bahia Honda State Park is a well known dark skies location among locals offering unobstructed views of the southern night sky year-round. It also hosts amateur astronomy gatherings.
in Florida Keys Astronomy Club Events
/ref>
See also
* Adam's Bridge
Notes
References
Other references
* Jeff, Ripple (1995). ''The Florida Keys: the Natural Wonders of an Island Paradise'', Photographs by Bill Keogh, Stillwater, Minnesota: Voyageur Press. .
Jason Project The Story of Water Movement and Land Formation
– accessed January 28, 2006.
*
Florida Keys Fish
External links
A Gazetteer of the Florida Keys
*
City of Key West
City of Marathon
NOAA Marine Sanctuary
*
Media
Key West Citizen
{{Authority control
Outstanding Florida Waters
Regions of Florida
South Florida
Archipelagoes of the United States