Highways in the United States are split into at least four different types of systems: Interstate Highways, U.S. Highways, state highways, and county highways.

Highway A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-acces ...

s are generally organized by a

route number A route (or road) number, designation or abbreviation is an identifying numeric (or alphanumeric) designation assigned by a highway authority to a particular stretch of roadway to distinguish it from other routes and, in many cases, also to indic ...

or letter. These designations are generally displayed along the route by means of a highway shield. Each system has its own unique shield design that will allow quick identification to which system the route belongs.

History

In 1918,

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

became the first state to number its highways in the field followed by

Michigan Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...

the following year. In 1926 the American Association of State Highway Officials (AASHO) established and numbered interstate routes (

United States Numbered Highways 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 ...

), selecting the best roads in each state that could be connected to provide a national network of federal highways.

Interstate Highways

The Interstate Highway System is a federally funded and administered but state-maintained system of

freeway 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 ...

s that forms the transportation backbone of the United States, with millions of Americans relying on it for commutes, long-distance travel, and freight transport daily, among other things. Interstate highways are all constructed to precise standards, designed to maximize high-speed travel safety and efficiency. Interstate Highways also contain auxiliary routes, which are normally assigned a three-digit route number. All Interstate Highways are part of the National Highway System, a network of highways deemed essential to the defense, economy, and mobility of the country.

U.S. Highways

The United States Numbered Highway System is an older system consisting mostly of surface-level trunk roads, coordinated by the

American Association of State Highway and Transportation Officials The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United ...

and maintained by state and local governments. U.S. Highways have been relegated to regional and intrastate traffic, as they have been largely supplanted by the Interstate system for long-distance travel except in areas (especially in the west) where the Interstate system is absent or underdeveloped. This has led to the decommissioning and truncation of U.S. Highways that were formerly vital long-haul routes, such as

U.S. Route 21 U.S. Route 21 or U.S. Highway 21 (US 21) is a major north–south United States Numbered Highway in the Southeastern United States that travels . The southern terminus is in Hunting Island State Park, South Carolina, south of the ...

and

U.S. Route 66 U.S. Route 66 or U.S. Highway 66 (US 66 or Route 66) was one of the original highways in the United States Numbered Highway System. It was established on November 11, 1926, with road signs erected the following year. The h ...

State highways

Each state also has a state highway system. State highways are of varying standards, capacity, and quality. Some state highways become so heavily traveled they are built to Interstate Highway standards. Others are more lightly traveled and have low capacity. Many state highway markers are designed to suggest the geographic shape of the state or some other state symbol such as its flag. Most of the others are generically rectangular or some other neutral shape. The default design for state highway markers is the circular highway shield, which is how state highways are indicated on most maps and atlases. Currently, five states—

Delaware Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Del ...

Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia ...

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

, and

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

—use the circular shield for road signage on their state highways.

Federal district and territory highways

There are also numbered highways in the

District of Columbia ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

and

territories A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

. Likewise, they may also vary in standards and quality.

Secondary highways

Some states may include a secondary highway system to supplement the main one, usually for a specific purpose. For example, Texas established a system of

farm-to-market road In the United States, a farm-to-market road or ranch-to-market road (sometimes farm road or ranch road for short) is a state highway or county road that connects rural or agricultural areas to market towns. These are better quality roads, usually ...

s to specifically improve access to rural areas. Nebraska has Connecting Link, Spur, and Recreation Highways to provide access to small towns and state parks. The

Missouri supplemental route A supplemental route is a state secondary road in the U.S. state of Missouri, designated with letters. Supplemental routes were various roads within the state which the Missouri Department of Transportation was given in 1952 to maintain in additi ...

system was designed to provide access to most farm houses, schools, churches, cemeteries, and stores within the state.

County highways

The final administrative level in some states is the county highway. As the name suggests, this type of road is maintained by a

county A county is a geographic region of a country used for administrative or other purposes Chambers Dictionary, L. Brookes (ed.), 2005, Chambers Harrap Publishers Ltd, Edinburgh in certain modern nations. The term is derived from the Old French ...

. County roads vary widely from well-traveled multilane highways to dirt roads into remote parts of the county. In Louisiana, parish roads exist in place of county highways, as counties in that state are called parishes. Alaska also has no counties, and all roads are maintained at the national, state or municipal level. In some states, such as Massachusetts, county roads are now administered by regional entities, and both Connecticut and Rhode Island have no county government and therefore no county highways. In New York and Ohio, each county has its own style of marker for its system of county roads, creating a wide variety of county road markers across those states.

Other systems

Other highway systems include: *

Forest Highway Forest Highways or Forest Routes are a category of roads within United States National Forests. They are built to connect the national forests to the existing state highway systems, and to provide improved access to recreational and logging area ...

: Highways connecting U.S. National Forests to the existing state highway systems, and thus provide improved access to recreational and logging areas. * Indian route: Highways found in several Indian reservations. * U.S. Bicycle Route: Part of the

national cycling route network A national cycling route network is a nationwide network of designated long-distance cycling routes found in various countries around the world for the purposes of bicycle tourism. They are often created and maintained by the government of the co ...

in the U.S., consisting of interstate

long-distance cycling route Long-distance cycling routes are designated cycling routes in various countries around the world for bicycle tourism. These routes include anything from longer rail trails, to national cycling route networks like the Dutch LF-routes,the French Ve ...

s that use multiple types of bicycling infrastructure, including off-road paths, bicycle lanes, and low-traffic roads. * Local highways: City and local governments may have their own highways, such as the Red, Yellow, and Blue Routes in

Branson, Missouri Branson is a city in the U.S. state of Missouri. Most of the city is situated in Taney County, with a small portion in the west extending into Stone County. Branson is in the Ozark Mountains. The community was named after Reuben Branson, postm ...

;

Charlotte Route 4 Route 4 is an partial ring road located in Charlotte, North Carolina. Beginning and ending at Interstate 85 (I-85), it loops south around Uptown Charlotte along state-maintained secondary roads, connecting the Charlotte Douglas International A ...

Charlotte, North Carolina Charlotte ( ) is the most populous city in the U.S. state of North Carolina. Located in the Piedmont region, it is the county seat of Mecklenburg County. The population was 874,579 at the 2020 census, making Charlotte the 16th-most populo ...

; the

Allegheny County Belt System The Allegheny County Belt System color codes miscellaneous county roads to form a unique system of routes in Allegheny County, Pennsylvania, and around the city of Pittsburgh. Unlike many major American cities that utilize number-coded limited-a ...

in and around

Pittsburgh, Pennsylvania Pittsburgh ( ) is a city in the Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County. It is the most populous city in both Allegheny County and Western Pennsylvania, the second-most populous city in Pennsylva ...

; and the

Inner Loop Inner loop may refer to: * Inner loop in computer programs * Inner Loop (Phoenix), a section of Interstate 10 in downtown Phoenix, Arizona, United States * Inner Loop (Rochester), an expressway around downtown Rochester, New York, United States * I ...

Rochester, New York Rochester () is a city in the U.S. state of New York, the seat of Monroe County, and the fourth-most populous in the state after New York City, Buffalo, and Yonkers, with a population of 211,328 at the 2020 United States census. Located in W ...

. * Some

townships A township is a kind of human settlement or administrative subdivision, with its meaning varying in different countries. Although the term is occasionally associated with an urban area, that tends to be an exception to the rule. In Australia, C ...

also maintain Township Routes.

References

External links

Full list of state route markersOld Trails - US and Canadian Roads in the 20th Century
(includes drawings and photos of old signs) {{US route types Route Numbered highways

United States numbered highways 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 ...