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. Highways are generally organized by a route number 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. Below is a list of the different highway shields used throughout the United States.
The Interstate Highway System is a federally funded and administered (but state-maintained) system of freeways that forms the transportation backbone of the U.S., with millions of Americans relying on it for commutes, long-distance travel, and freight transport daily. 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.
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 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 and U.S. Route 66.
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 designated on most maps and atlases. Currently, five states—Delaware, Iowa, Kentucky, Mississippi, and New Jersey—use the circular shield for road signage on their state highways.
There are also numbered highways in the District of Columbia and territories. Likewise, they may also vary in standards and quality.
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 roads 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 system was designed to provide access to most farm houses, schools, churches, cemeteries, and stores within the state.
The final administrative level in some states is the county highway. As the name suggests, this type of road is maintained by a county. 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 Ohio, each county has its own style of marker for its system of county roads, creating a wide variety of county road markers across the state.
Other highway systems include:
In 1918, Wisconsin became the first state to number its highways in the field.In 1926 the American Association of State Highway Officials (AASHO) established and numbered interstate routes (United States Numbered Highways), selecting the best roads in each state that could be connected to provide a national network of federal highways.
The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Construction of the system was authorized by the Federal Aid Highway Act of 1956. The system extends throughout the contiguous United States and has routes in Hawaii, Alaska, and Puerto Rico.
The United States Numbered Highway System 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 highways were coordinated among the states, they are sometimes called Federal Highways, but the roadways were built and have always been maintained by state or local governments since their initial designation in 1926.
A state highway, state road, or state route is usually a road that is either numbered or maintained by a sub-national state or province. A road numbered by a state or province falls below numbered national highways in the hierarchy. Roads maintained by a state or province include both nationally numbered highways and un-numbered state highways. Depending on the state, "state highway" may be used for one meaning and "state road" or "state route" for the other.
Highways in Australia are generally high capacity roads managed by state and territory government agencies, though Australia's federal government contributes funding for important links between capital cities and major regional centres. Prior to European settlement, the earliest needs for trade and travel were met by narrow bush tracks, used by tribes of Indigenous Australians. The formal construction of roads began in 1788, after the founding of the colony of New South Wales, and a network of three major roads across the colony emerged by the 1820s. Similar road networks were established in the other colonies of Australia. Road construction programs in the early 19th century were generally underfunded, as they were dependent on government budgets, loans, and tolls; while there was a huge increase in road usage, due to the Australian gold rushes. Local government authorities, often known as Road Boards, were therefore established to be primarily responsible for funding and undertaking road construction and maintenance. The early 1900s saw both the increasingly widespread use of motorised transportation, and the creation of state road authorities in each state, between 1913 and 1926. These authorities managed each state's road network, with the main arterial roads controlled and maintained by the state, and other roads remaining the responsibility of local governments. The federal government became involved in road funding in the 1920s, distributing funding to the states. The depression of the 1930s slowed the funding and development of the major road network until the onset on World War II. Supply roads leading to the north of the country were considered vital, resulting in the construction of Barkly, Stuart, and Eyre Highways.
A routenumber is an identifying numeric designation assigned by a highway authority to a particular stretch of roadway to distinguish it from other routes and, in many cases, also to indicate its classification, general geographical location and/or orientation. The numbers chosen may be used solely for internal administrative purposes; however, in most cases they are also displayed on roadside signage and indicated on maps.
The U.S. Route shield is the highway marker used for United States Numbered Highways. Since the first U.S. Route signs were installed in 1926, the general idea has remained the same, but many changes have been made in the details. Originally, the shield included the name of the state in which the sign was erected and the letters "U S" on a shield-shaped sign. Over time, the shield has been simplified to consist of a white shield outline on a black square background, containing only a black route number. However, because each state is responsible for the production and maintenance of U.S. Route shields, several variants of the shield have existed over the years.
A business route in the United States is a short special route connected to a parent numbered highway at its beginning, then routed through the central business district of a nearby city or town, and finally reconnecting with the same parent numbered highway again at its end.
A county highway is a road in the United States and in the Canadian province of Ontario that is designated and/or maintained by the county highway department. Route numbering can be determined by each county alone, by mutual agreement among counties, or by a statewide pattern.
The Massachusetts State Highway System in the U.S. state of Massachusetts is a system of state-numbered routes assigned and marked by the highway division of the Massachusetts Department of Transportation (MassDOT). U.S. Highways and Interstate Highways are included in the system; the only overlaps are with the end-to-end U.S. Route 3 and Route 3 and the far-apart Interstate 295, shared with Rhode Island, and Route 295, shared with New York State. A state highway in Massachusetts is a road maintained by the state, which may or may not have a number. Not all numbered routes are maintained or owned by the state.
In the state of Maine, the Maine Department of Transportation (MaineDOT) has a system of numbered highways, defined as the "connected main highways throughout the state which primarily serve arterial or through traffic." As of 2006, 22,236 miles of roadway are included in the highway system, including Interstate highways, U.S. Routes, state highways, and other urban and rural local roads.
A highway shield or route marker is a sign denoting the route number of a highway, usually in the form of a symbolic shape with the route number enclosed. As the focus of the sign, the route number is usually the sign's largest element, with other items on the sign rendered in smaller sizes or contrasting colors. Highway shields are used by travellers, commuters, and all levels of government for identifying, navigating, and organising routes within a county, state, province, or country. Simplified highway shields often appear on maps.
The Nebraska State Highway System consists of all the state highways in Nebraska maintained by the Nebraska Department of Roads. This includes federally designated Interstates and US Highways as well as state highways, links and spurs. The system comprises 9,942 miles (16,000 km) of state highways in all 93 counties. Highways within the system range in scale and quality from 10-lane urban freeways, such as I-80 around Omaha, to standard two-lane rural undivided highways as well as 39 miles (63 km) of state highways that remain unpaved such as N-67 north of Dunbar. Surrounding landscapes along the highway system range from the urban areas in Omaha and Lincoln to scenic journeys through uninhabited grasslands in the Nebraska Sandhills.
In road transportation in the United States, a special route is a road in a numbered highway system that diverts a specific segment of related traffic away from another road. They are featured in many highway systems; most are found in the Interstate Highway System, U.S. highway system, and several state highway systems. Each type of special route possesses generally defined characteristics and has a defined relationship with its parent route. Typically, special routes share a route number with a dominant route, often referred as the "parent" or "mainline", and are given either a descriptor which may be used either before or after the route name, such as Alternate or Business, or a letter suffix that is attached to the route number. For example, an alternate route of U.S. Route 1 may be called "Alternate U.S. Route 1", "U.S. Route 1 Alternate", or "U.S. Route 1A". Occasionally, a special route will have both a descriptor and a suffix, such as U.S. Route 1A Business.
An unsigned highway is a highway that has been assigned a route number, but does not bear road markings that would conventionally be used to identify the route with that number. Highways are left unsigned for a variety of reasons, and examples are found throughout the world. Depending on the policy of the agency that maintains the highway, and the reason for not signing the route, the route may instead be signed a different designation from its actual number, with small inventory markers for internal use, or with nothing at all.
In the U.S. state of Pennsylvania, state highways are generally maintained by the Pennsylvania Department of Transportation (PennDOT). Each is assigned a four-digit State Route (SR) number in the present Location Referencing System. Traffic Routes are signed as Interstate Highways, U.S. Routes and Pennsylvania Routes, and are prefixed with one to three zeroes to give a four-digit number. PA Routes are also called Pennsylvania Traffic Routes, and formerly State Highway Routes.
In the United States, road signs are, for the most part, standardized by federal regulations, most notably in the Manual on Uniform Traffic Control Devices (MUTCD) and its companion volume the Standard Highway Signs (SHS). There are no plans for adopting the Vienna Convention on Road Signs and Signals standards.
The primary highway system makes up over 9,000 miles (14,000 km), a mere 8 percent of the U.S. state of Iowa's public road system. The Iowa Department of Transportation is responsible for the day-to-day maintenance of the primary highway system, which consists of Interstate Highways, United States Highways, and Iowa state highways. Currently, the longest primary highway is U.S. Route 30 at 332 miles (534 km). The shortest highway is Interstate 129 at 0.27 miles (0.43 km).
The Arkansas Highway System is made up of all the highways designated as Interstates, U.S. Highways and State Highways in the US state of Arkansas. The system is maintained by the Arkansas Department of Transportation (ArDOT), known as the Arkansas State Highway Department (AHD) until 1977 and the Arkansas State Highway and Transportation Department (AHTD) from 1977 to 2017. The system contains 16,442.90 miles (26,462.28 km) of Interstates, U.S. Routes, state highways, and special routes. The shortest members are unsigned state highways Arkansas Highway 806 and Arkansas Highway 885, both 0.09 miles (0.14 km) in length. The longest route is U.S. Route 67, which runs 296.95 miles (477.89 km) from Texarkana to Missouri.
The Delaware State Route System consists of roads in the U.S. state of Delaware that are maintained by the Delaware Department of Transportation (DelDOT). The system includes the portions of the Interstate Highway System and United States Numbered Highways system located in the state along with state routes and other roads maintained by DelDOT. All roads maintained by the state are assigned a maintenance road number that is only marked on little white markers at intersections and on auxiliary plates below warning signs approaching intersections. These numbers are only unique in a specific county, some roads can be designated with multiple road numbers, and numbers do not necessarily correspond to the signed Interstate, U.S., or state route numbers. DelDOT maintains a total of 5,386.14 miles (8,668.15 km) of roads, comprising 89 percent of the roads within the state. Some large bridges in the state are maintained by other agencies including the U.S. Army Corps of Engineers and the Delaware River and Bay Authority. Roads in the system include multilane freeways, multilane surface divided highways, and two-lane undivided roads serving urban, suburban, and rural areas. Some of the roads maintained by DelDOT are toll roads, in which motorists must pay to use.
The Roads in Puerto Rico are the national, forest and municipal roadways that make up the approximately 14,400 kilometers (8,900 mi) roads through the terrain of Puerto Rico. The highways serve the more than 3 million residents, and 3-4 million tourists who visit each year.
Guidance: State Route signs...should be rectangular and should be approximately the same size as the U.S. Route sign....The shape of the white area should be circular in the absence of any determination to the contrary by the individual State concerned.
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