U.S. Highway 18 (US 18) is the northernmost east–west

United States Numbered Highway The United States Numbered Highway System (often called U.S. Routes or U.S. Highways) is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these h ...

in the state of

Iowa Iowa ( ) is a U.S. state, state in the upper Midwestern United States, Midwestern region of the United States. It borders the Mississippi River to the east and the Missouri River and Big Sioux River to the west; Wisconsin to the northeast, Ill ...

. As with all

state highways A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either Route number, numbered or maintained by a sub-national state or province. A road numbered ...

in Iowa, it is maintained by the

Iowa Department of Transportation The Iowa Department of Transportation (Iowa DOT) is the government organization in the U.S. state of Iowa responsible for the organization, construction, and maintenance of the List of Iowa state highways, primary highway system. Located in Am ...

(Iowa DOT). It enters the state by crossing the

Big Sioux River The Big Sioux River is a tributary of the Missouri River in eastern South Dakota and northwestern Iowa in the United States. It flows generally southwardly for ,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataTh ...

between Inwood and

Canton, South Dakota Canton is a city in and the county seat of Lincoln County, South Dakota, United States. Canton is located 20 minutes south of Sioux Falls in southeastern South Dakota. Canton is nestled in the rolling hills of the Sioux Valley, providing an abund ...

. It travels about and connects Spencer, Mason City, and Charles City. The highway leaves the state via the

Marquette–Joliet Bridge The Marquette–Joliet Bridge is a bridge crossing the Mississippi River, connecting Marquette, Iowa and Prairie du Chien, Wisconsin. Local residents refer to the bridge as the Prairie Bridge or the Marquette Bridge; both terms are used equally ...

over the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

at Marquette. Prior to becoming a U.S. Highway, the route US 18 follows was known as Primary Road No. 19 and the National Parks Pike.

Route description

US 18 begins at the

approximately east of

. It runs easterly through rural Lyon County, in the northwestern corner of the state. At Inwood, it meets

Iowa Highway 182 Iowa Highway 182 (Iowa 182) is a state highway in the northwestern corner of Iowa. It begins at U.S. Highway 18 (US 18) in Inwood and ends at Iowa 9 southeast of Larchwood. The highway has been in the primary highway system ...

(Iowa 182), which provides access to

Sioux Falls, South Dakota Sioux Falls ( ) is the List of cities in South Dakota, most populous city in the U.S. state of South Dakota and the List of United States cities by population, 117th-most populous city in the United States. It is the county seat of Minnehaha Coun ...

, via Iowa 9 and

South Dakota Highway 42 South Dakota Highway 42 (SD 42) is a segmented state highway in southeastern South Dakota, United States. The first segment is a highway in Aurora County. The second and longest is long and connects Ethan and Sioux Falls. The final se ...

. US 18 turns south at Inwood and heads into Sioux County. The highway crosses the Rock River on its way toward Rock Valley and

Hull Hull may refer to: Structures * The hull of an armored fighting vehicle, housing the chassis * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a sea-going craft * Submarine hull Ma ...

. West of Hull, at

Perkins Perkins is a surname derived from the Anglo-Saxon corruption of the kin of Pierre (from Pierre kin to Pierrekin to Perkins), introduced into England by the Norman Conquest. It is found throughout mid- and southern England. Another derivation com ...

, US 18 juts to the south along US 75 before turning east again closer to Hull. The highway continues east toward Sheldon. As it crosses into O'Brien County on the western edge of Sheldon, US 18 intersects Iowa 60 Business (Iowa 60 Bus.). The two routes head east toward a

diamond interchange A diamond interchange is a common type of road junction, used where a controlled-access highway crosses a minor road. Design The freeway itself is grade separation, grade-separated from the minor road, one crossing the other over a bridge. ...

with Iowa 60 on the eastern side of town where the business loop ends. The highway roughly parallels the

Dakota, Minnesota and Eastern Railroad The Dakota, Minnesota and Eastern Railroad is a wholly owned U.S. subsidiary of the Canadian Pacific Kansas City. Before its purchase, it was the largest Class II railroad in the United States, operating across South Dakota and southern Minnesot ...

(DM&E Railroad). In Sanborn, US 18 is briefly overlapped by US 59, which joins from the north and leaves to the south. Continuing east, it passes through

Hartley Hartley may refer to: Places Australia *Hartley, New South Wales * Hartley, South Australia ** Electoral district of Hartley, a state electoral district Canada * Hartley Bay, British Columbia United Kingdom * Hartley, Cumbria * Hartley, P ...

and then enters

Clay County Clay County is the name of 18 counties in the United States. Most are named for Henry Clay, U.S. Senator and statesman: * Clay County, Alabama * Clay County, Arkansas (named for John Clayton, and originally named Clayton County) * Clay County, Fl ...

. North of Spencer, it intersects US 71 and the two routes head south together through town. On the south side of Spencer, the two routes come to a

T intersection A three-way junction (or three-way intersection) is a type of road intersection with three arms. A Y junction (or Y intersection) generally has three arms of equal size coming at an acute or obtuse angle to each other; while a T junction (or T ...

and each route heads in the opposite direction—US 18 to the east and US 71 to the west. East of Spencer, US 18 passes through Ruthven in Palo Alto County. Between Ruthven and

Emmetsburg Emmetsburg is a city in Palo Alto County, Iowa, Palo Alto County, Iowa, United States. The population was 3,706 at the time of the 2020 United States census, 2020 census. It is the county seat of Palo Alto County. Emmetsburg is located around th ...

, it is joined by Iowa 4 from the north. The two routes split again in Emmetsburg as Iowa 4 heads south. US 18 continues east, briefly heading south to enter

Cylinder A cylinder () has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite ...

. The route curves back to the east at the DM&E Railroad line. An intersection with Iowa 15 near Whittemore marks the Palo Alto– Kossuth county line. Iowa 15 follows US 18 for before it splits away to the north. On the northern edge of Algona, the highway meets US 169. At the eastern county line, shared with Hancock County, is an intersection with Iowa 17, which marks that route's northern end. In Hancock County, the route passes through

Britt Britt may refer to: Places * Britt, Iowa, United States * Britt, Minnesota, United States * Britt, Ontario, Canada * Britt Peak, Marie Byrd Land, Antarctica * Britt Township, Hancock County, Iowa, United States Other uses * Britt (actress), Swedi ...

before meeting US 69 west of Garner; the two highways split in Garner. East of Garner, the route takes a north-northeasterly path as it goes through Ventura and skirts the northern shore of Clear Lake. Near the northeastern shore of the lake, it enters the city of Clear Lake, where it meets Interstate 35 (I-35). Iowa 122 and US 18 Bus. head east from the interchange with the Interstate. US 18 traffic follows southbound I-35 for .

Iowa 27 The Avenue of the Saints is a highway in the Midwestern United States that connects St. Louis, Missouri, and St. Paul, Minnesota. __TOC__ Route description Missouri The southern end of the Avenue of the Saints is at exit 28A on Interstate ...

, the Avenue of the Saints highway, which had hitherto followed I-35 southbound now follows US 18 eastbound. The two routes, now on a four-lane,

controlled-access highway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...

, follow a path which passes to the south of Mason City. They meet US 65 and US 18 Bus. at exit 186. Charles City wind farm

At the Floyd county line, US 18 and Iowa 27 become a

limited-access road A limited-access road, known by various terms worldwide, including limited-access highway, partial controlled-access highway, and expressway, is a highway or arterial road for high-speed traffic which has many or most characteristics of a contro ...

and angle slightly to the northeast, passing

Rudd ''Scardinius'' is a genus of freshwater ray-finned fishes belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related species. The fishes in this genus are commonly called rudds. Locally, the name "rudd" without ...

. At Floyd, the two routes are joined by US 218. The three routes head south along a bypass of Charles City. They intersect Iowa 14 on the western side of town and take a 90-degree curve to the east. At exit 218 of the expressway, US 18 leaves US 218 and Iowa 27, which continue southeastward toward Cedar Falls–

Waterloo Waterloo most commonly refers to: * Battle of Waterloo, 1815 battle where Napoleon's French army was defeated by Anglo-allied and Prussian forces * Waterloo, Belgium Waterloo may also refer to: Other places Australia * Waterloo, New South Wale ...

. US 18 briefly heads north into Charles City with US 218 Bus. The two routes meet the northern end of Iowa 14, and US 18 splits away to the east to cross the Cedar River. Heading east again, the route enters Chickasaw County and passes through Bassett on its way to New Hampton. It meets US 63 at a four-lane bypass on the western side of town. The two routes head south for , splitting at the mile 196 interchange which is also the eastern end of Iowa 346. The route turns to travel due east through Fredericksburg. Continuing due east, US 18 does not enter another community for until it reaches West Union in Fayette County. In West Union, it intersects Iowa 150. East of town, it crosses into the

Driftless Area The Driftless Area, also known as Bluff Country and the Paleozoic Plateau, is a topographic and cultural region in the Midwestern United States that comprises southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme ...

, an area that was untouched by glaciation during the last ice age. The route turns to the northeast to through Clermont and then to the north to meet US 52 at

Postville Postville is a city in Allamakee County, Iowa, Allamakee and Clayton County, Iowa, Clayton counties in the U.S. state of Iowa. It lies near the junction of four counties and at the intersection of U.S. Routes U.S. Route 18 in Iowa, 18 and U.S. Ro ...

in southern Allamakee County. The two routes head east through Postville and turn south into Clayton County. Near Froelich, US 52 leaves to the south toward

Dubuque Dubuque (, ) is a city in Dubuque County, Iowa, United States, and its county seat. The population was 59,667 at the 2020 United States census. The city lies along the Mississippi River at the junction of Iowa, Illinois, and Wisconsin, a region ...

. Heading to the northeast toward

McGregor McGregor may refer to: People * McGregor (surname) * Clan MacGregor, a Scottish highland clan * McGregor W. Scott (born 1962), U.S. attorney Places in Canada: * McGregor Lake, Alberta; a lake * McGregor, British Columbia * McGregor Plateau, Nec ...

and Marquette, its

business loop A business route (or business loop, business spur, or city route) in the United States is a short special route that branches off a parent numbered highway at its beginning, continues through the central business district of a nearby city or t ...

goes through the towns while the mainline skirts around them. The business loop rejoins the mainline at the foot of the

, which spans the

. US 18 continues east into

Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig ...

with State Trunk Highway 60, which begins at the state line.

History

Before it and the rest of the U.S. Numbered Highway System were designated on November 11, 1926, US 18 was known by two names in the state. It was first known as Primary Road No. 19, which was assigned to the route when the

Iowa State Highway Commission The Iowa Department of Transportation (Iowa DOT) is the government organization in the U.S. state of Iowa responsible for the organization, construction, and maintenance of the primary highway system. Located in Ames, Iowa, DOT is also respon ...

published its first state highway map in 1919. The route was also called the

National Parks Pike National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...

, which began at

Yellowstone National Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

and ended in

Madison, Wisconsin Madison is the List of capitals in the United States, capital city of the U.S. state of Wisconsin. It is the List of municipalities in Wisconsin by population, second-most populous city in the state, with a population of 269,840 at the 2020 Uni ...

, encompassing all of Primary Road No. 19 in the state. The pike was registered with the on April 29, 1920. The National Parks Pike name fell into disuse after the highway became US 18. By 1927, a significant portion of the route was paved, while the remainder was graveled. All of O'Brien County and between Algona and Charles City were paved. In seven years, the gap between O'Brien County and Algona was finished which created of continuous pavement. During those same seven years, the route from West Union to the

and all of Primary Road No. 59, which included the overlap of US 18 near New Hampton were paved. Primary Road No. 59 is now known as US 63. By the start of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, the only remaining section of US 18 that was not paved was an section west of Rock Valley in Sioux County. That last section would not be completed for another 10 years. Prior to 1932, the only way vehicles traveling US 18 could cross the Mississippi River was by ferry. That changed in when identical suspension bridges were built to cross the river between Marquette and

Prairie du Chien, Wisconsin Prairie du Chien ( ) is a city in Crawford County, Wisconsin, United States, and its county seat. The population was 5,506 at the 2020 census. Often called Wisconsin's second-oldest city, Prairie du Chien was established as a European settlemen ...

. Built in 1931–1932, each bridge was long, crossed a main channel of the river, and were divided by a island causeway. The first car to cross the bridges did so on March 7, 1932. Users of the bridge had to pay a toll until July 15, 1954. The bridges remained in use for another 20 years, when they were replaced by the

. In 1988–1989, a bypass was built around

so US 18 could connect directly to the Marquette–Joliet Bridge. A short road had previously provided access to and from the bridge. The old alignment of the route became US 18 Bus. Over the late 1990s, construction began on the

Avenue of the Saints The Avenue of the Saints is a highway in the Midwestern United States that connects St. Louis, Missouri, and St. Paul, Minnesota. __TOC__ Route description Missouri The southern end of the Avenue of the Saints is at exit 28A on Interstate ...

corridor near Mason City. A new controlled-access facility was built south of the city east to

. On December 5, 1999, this section of freeway opened and US 18 was realigned onto the new road. The old alignment became Iowa 122. By the end of the next year, the four-lane expressway was extended to Charles City. By 2003, an expressway carrying US 63 was built around New Hampton. US 18 was rerouted onto the expressway and the western end of Iowa 24 was moved to the US 63/US 18 interchange.

Major intersections

References

External links

Route description

History

Major intersections

See also

References

External links