in
Hobart, Oklahoma ends at its parent route. The center SH-9 shield is topped with a typical "BUSINESS" sign. Routes with special designations in the U.S. have typical behavior that distinguishes them from other routes. There are, however, many exceptions to the common behavior, depending on the situation.
Business, City, and Bypass routes Business routes (also known as city routes) can be loops or spurs and generally traverse through or near population centers (usually towns and small cities). They are usually signed with "" or "" auxiliaries or a "B" suffix. Most business routes are the former alignments of their parent. Bypass routes (rarely known as "Relief routes") typically go around population centers and are newer and faster than their mainline and/or business route counterparts. In some cases, due to
urban sprawl over time, land around bypasses can become developed, expanding the population center outward and creating a misnomer with the term "bypass". Approaching a population center, it is common for the parent route to split between a business route and a bypass route and rejoin to form the parent on the other side. AASHTO defines a business route for U.S. highways as ...a route principally within the corporate limits of a city which provides the traveling public an opportunity to travel through that city, passing through the business part of the city; while the regular number is used to obviate passing through the congested part of the city. This "Business Route" connects with the regular numbered route at the opposite side of the city limits. AASHTO defines bypass or relief routes for U.S. highways as: ...a route which is established for the purpose of designating a route which entirely by-passes a city or congested area and joins in with the regular numbered route beyond the city or congested area. Known as
Business Loops and
Business Spurs, these routes that principally travel through the corporate limits of a city, passing through the
central business district of the city. Business routes are used when the regular route is directed around the city. with obstacles (such as low clearance bridges, sharp turns, or steep
grades) or with conditions that could create dangerous situations to smaller vehicles. An example of such a route is
U.S. Route 1/9 Truck in
New Jersey, which bypasses the segment of
U.S. Route 1/9 that uses the
Pulaski Skyway, on which trucks are banned.
Alternate Truck Routes There are alternate truck routes in several counties in southeastern
Pennsylvania. They bypass weight-restricted bridges over creeks and rivers. They are mainly routed on major highways and freeways and other roads they intersect to bypass that specific bridge. An example of an alternate truck route is
Pennsylvania Route 82 Alternate Truck which bypasses a weight-restricted bridge over East Branch of Red Clay Creek. Most of the alternate truck routes were signed in 2013, though some were signed as recently as 2023.
Alternate and Optional routes serves as an alternate alignment to
U.S. Route 58 in the western part of
Virginia Alternate routes are loops that provide alternative alignment for a parent route. They are usually signed with an "" or "" auxiliary or an "A" suffix. They generally traverse through a different settlements or different city neighborhoods than the parent route, but roughly remain parallel to the parent. Unlike business routes and bypasses, their relationship to population centers varies from case to case. Alternates also can be quite longer than most other special routes with some spanning over 50 miles (e.g.
US 1A in
Maine and
US 74A in
North Carolina). Prior to 1960 there were "optional" routes in the United States that were synonymous with alternate routes. As a means of providing uniformity, the "Optional" term was phased out in the 1960s.
Spur routes Spur routes split away from the parent route without returning. They usually end in a settlement or area not served by the parent.
Connector routes in Georgia in Michigan A connector is a highway or freeway road in the United States that connects to another highway or freeway. It can be part of an
interchange such as the
MacArthur Maze in
Oakland, California, or a longer roadway such as the
Interstate 635 in the
Kansas City metropolitan area. A connector route is a type of special route or supplemental route in the United States that serves as a connector, connecting one route to a more prominent route. Connector routes are found among the
United States Numbered Highways and among some
state route systems like
Michigan and
Nebraska. Connector routes can also be designated as a routing between two numbered highways. Examples include
Connector M-44, which runs along Plainfield Avenue between
Interstate 96 and
M-44 north of
Grand Rapids, Michigan, and
Pearl Harbor Memorial Turnpike Extension (also known as the Pennsylvania Turnpike Connector), which connects the
New Jersey Turnpike with the
Delaware River extension of the
Pennsylvania Turnpike.
Scenic routes Scenic routes, in terms of special routes, are loops of a parent route that traverse through an area of natural or historical significance. Only one route in the country remains with the official Scenic designation:
US 40 Scenic.
Toll routes in Pennsylvania Toll routes, in terms of special routes, are loops that are faster than the parent route, but are
tolled. The other usage with the promulgation of the 2009 MUTCD is to use a yellow toll plate above the marker along tolled segments of highways.
Loop routes is a loop route. Loop routes, in terms of special routes, are loops that form a complete radial around an area, having at least one intersection with the parent route. Because of their circumferential nature,
inner/outer directions have been used to sign such routes, as opposed to
cardinal directions, though this convention is not universally followed (Arizona Loops
101,
202, and
303 in the
Phoenix metropolitan area do not follow such convention, and are signed with cardinal directions based on their local orientation).
Georgia State Route 10 Loop, which is the perimeter highway around
Athens, Georgia, and the former
Georgia State Route 120 Loop, which encircled a section of
Marietta, Georgia, are two examples. Loop routes are common throughout Texas; see
List of state highway loops in Texas.
Temporary routes Temporary signage in
Haddonfield, New Jersey Temporary routes complete a gap between two segments of a parent route that exists because the parent route through the area has not been fully constructed. They serve as a long-term detour until the parent route's planned path is completed, at which point the Temporary designation is either removed or replaced by another designation such as Alternate or Business. Temporary routes generally traverse along roads of a lower standard than the planned mainline. An example is
US 191 through a copper mine north of
Clifton, Arizona. AASHTO defines and specifies that temporary routes should have the following behavior: In the erection of signs for numbering routes, it is necessary in some cases to carry a number temporarily over a road that ultimately will not be the permanent location of that number. Great care should be taken by the State Highway Departments in seeing that when numbers of this character are permitted, that a standard strip carrying the words "Temporary" shall be placed on the staff above the number. This will obviate much hard feeling when it is necessary to change a number to the permanently established route.
Emergency detour routes A rare type of special route, known as the Emergency Detour route, is signed with an auxiliary "Emergency" sign that is colored orange, indicating a temporary traffic control sign. The purpose of these routes is to offer an alternative in case the parent route is impassable, due to either a
traffic jams,
traffic collision, or road closure (for a variety of reasons).
Divided routes splits in
Tennessee into
US 25E and
US 25W Some
U.S. Routes are given directional suffixes to indicate a split of the main route — for instance,
U.S. Route 25 splits into
U.S. Route 25E (east) and
U.S. Route 25W (west) between
Newport, Tennessee and
North Corbin, Kentucky, and
U.S. Route 9W is an alternate of
U.S. Route 9 between
Fort Lee, New Jersey and
Albany, New York. These splits were in the system of
United States Numbered Highways from the beginning, and were used when two roughly equivalent routes existed. They are usually loops, but some have been spurs, though since they use directional letter suffixes, they are not generally considered special routes. AASHTO no longer assigns these numbers, and in theory current ones are to be eliminated "as rapidly as the State Highway Department and the Standing Committee on Highways can reach agreement". This policy was adopted by 1996; however, many of these routes still exist, mostly in
Tennessee. ==History==