An unsigned highway is a highway that has been assigned a route number, but does not bear conventional road markings that would normally be used to identify the route with that number. Depending on the policy of the agency that maintains the highway, 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.

Background

Routes are often left unsigned when they are extremely short. Roads that serve as a short connector to a major highway are sometimes signed to show the connection to the major road, rather than the road's actual designation.

Some highway maintenance agencies have separate numbering systems for their minor and major routes. To avoid confusion from having multiple highways in the same area with the same number, often the minor routes will be signed differently, or not signed at all. Other agencies use multiple numbering systems for the same set of routes; one number used for public signs and an internal numbering system for inventory purposes. In this case a highway may be unsigned as it has only been assigned an inventory designation, but not assigned a number in the public system.

Some highways are not signed to avoid multiple designations, such as when the entire route runs concurrent

Concurrency (road)

A concurrency, overlap, or coincidence in a road network is an instance of one physical road bearing two or more different highway, motorway, or other route numbers...

 with other highways, or the route has been assigned both name and a number. In countries where multiple agencies can create and number highways, a situation can occur where a road was built and signed by one agency, and later adopted or upgraded to become part of another network; yet is only signed with one of the designations. A situation unique to the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 is where some states assign state route inventory numbers to the U.S. Highways and Interstate Highways that enter the state.

Examples of major unsigned highways

• In several cities in the United States a short connector freeway is assigned a number in the Interstate Highway System; however, the freeway also carries one or more longer highway designations through the downtown area. In some cases, the freeway is only signed as one of the through designations and the short Interstate designation is omitted. Examples include Interstate 444
  Interstate 444
  Interstate 444 is an unsigned auxiliary route of the Interstate Highway System, with both ends at Interstate 244 in downtown Tulsa, Oklahoma. It makes up the eastern and southern sections on the square-shaped Inner Dispersal Loop....
  
  , Interstate 305 and Interstate 595
  Interstate 595 (Maryland)
  Interstate 595 is an unsigned number for a section of the John Hanson Highway from Interstate 495 east of Washington, D.C. to Maryland Route 70 at Annapolis, Maryland....
  
  , all of which are signed only with the U.S. Highway designations.
• None of the U.S. Highways that enter Yellowstone National Park
  Yellowstone National Park
  Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...
  
   are signed within park boundaries.
• The Interstate Highway System
  Interstate Highway System
  The Dwight D. Eisenhower National System of Interstate and Defense Highways, , is a network of limited-access roads including freeways, highways, and expressways forming part of the National Highway System of the United States of America...
  
   includes highways outside the Contiguous United States
  Contiguous United States
  The contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada and north of Mexico, plus the District of Columbia....
  
  . While the interstate highways in Hawaii
  Hawaii
  Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
  
   are signed similar to those in the contiguous United states, those in Alaska
  Interstate Highways in Alaska
  There are four officially designated Interstate Highways in Alaska, even though the routes do not connect directly to any highways in the contiguous United States, except either by the Alaska Marine Highway System ferries or via Canadian highways....
  
   and Puerto Rico are not signed with Interstate highway shields.
• Interstate 4 is internally designated by the Florida Department of Transportation
  Florida Department of Transportation
  The Florida Department of Transportation is a decentralized agency charged with the establishment, maintenance, and regulation of public transportation in the state of Florida. The department was formed in 1969. It absorbed the powers of the Florida State Road Department...
  
   as State Road 400; however, the state designation continues after I-4 has ended, and SR 400 signs do exist on the portion beyond the termini of I-4.
• Many named toll roads, turnpikes and parkways in the eastern United States are assigned route numbers by the owning agency, but are only publicly signed with a name. Examples include Florida's Turnpike
  Florida's Turnpike
  Florida's Turnpike , designated as the Ronald Reagan Turnpike, and originally known as the Sunshine State Parkway is a north–south toll road that runs through 11 counties in the Florida peninsula, from U.S...
  
   (officially State Road 91), the Garden State Parkway
  Garden State Parkway
  The Garden State Parkway is a 172.4-mile limited-access toll parkway that stretches the length of New Jersey from the New York line at Montvale, New Jersey, to Cape May at New Jersey's southernmost tip. Its name refers to New Jersey's nickname, the "Garden State." Most New Jersey residents refer...
  
   (officially Route 444), the southern portion of the New Jersey Turnpike
  New Jersey Turnpike
  The New Jersey Turnpike is a toll road in New Jersey, maintained by the New Jersey Turnpike Authority. According to the International Bridge, Tunnel and Turnpike Association, the Turnpike is the nation's sixth-busiest toll road and is among one of the most heavily traveled highways in the United...
  
   (officially Route 700), and the Atlantic City–Brigantine Connector, a spur off the Atlantic City Expressway
  Atlantic City Expressway
  The Atlantic City Expressway is a , controlled-access toll road in New Jersey, managed and operated by the South Jersey Transportation Authority...
  
  , officially numbered Route 446X and Route 446 respectively.
• The East Los Angeles Interchange
  East Los Angeles Interchange
  The East Los Angeles Interchange complex is the busiest freeway interchange in the world, with its southern portion handling over 550,000 vehicles per day . The northern portion, called the San Bernardino Split, is often considered a separate interchange. The interchange was named the Eugene A....
  
   is a case where a highway is unsigned with a conflict between the state and federal definition of a highway. The state definition of Interstate 10
  Interstate 10 in California
  Interstate 10 , the major east–west Interstate Highway in the Southern United States, runs in the U.S. state of California east from Santa Monica, on the Pacific Ocean, through Los Angeles and San Bernardino to the border with Arizona...
  
   has a discontinuity with a stub freeway proceeding west from the northern part of this interchange towards U.S. Route 101, while the federal definition of I-10 is contiguous. The discrepancy is resolved by having the signage at the interchange imply I-10 proceeds south through the main portion of interchange concurrent with I-5. The I-10 stub is signed US 101 while driving west and I-5/10 driving east.
• An unusual case is Washington State Route 41, which is the unsigned designation for a brief portion of Idaho State Highway 41
  Idaho State Highway 41
  State Highway 41, abbreviated SH-41, is a state highway mostly in the U.S. state of Idaho. It runs from Interstate 90 in Post Falls to U.S. Route 2 on the Washington state line. The northernmost of SH-41 run along State Street along the state line, with the southbound lane in the town of...
  
   that crosses the state line. Wyoming Highway 70
  Wyoming Highway 70
  Wyoming Highway 70 is known mainly as Battle Highway and travels from Wyoming Highway 789 in Baggs east to Wyoming Highway 230 in Riverside. WYO 70 over Battle Pass is closed during winter - Route description :...
  
   also dips into an adjacent state without any signage from the other state; however, in this case the road is entirely maintained by a single department of Transportation
  Department of Transportation
  The Department of Transportation is the most common name for a government agency in North America devoted to transportation. The largest is the United States Department of Transportation, which oversees interstate travel. All U.S. states, Canadian provinces, and many local agencies also have...
  
   and does not have a Colorado highway designation.

Entire unsigned route systems

The C, D, and U road systems in the Great Britain road numbering scheme

Great Britain road numbering scheme

The Great Britain road numbering scheme is a numbering scheme used to classify and identify all roads in Great Britain. Each road is given a single letter, which represents the road's category, and a subsequent number, with a length of between 1 and 4 digits. Originally introduced to arrange...

 are systems of routes considered less important than B roads and typically left unsigned.

In New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

, state-maintained highways that are not part of a signed state route are assigned a reference route designation. Reference route designations are signed only with reference marker

Reference marker (New York)

In New York, a reference marker is a small green sign mounted approximately every one-tenth mile on highways maintained by the New York State Department of Transportation. This was initiated in response to the Highway Safety Act of 1966 enacted by Congress, in an effort to monitor traffic and...

s, small green signs posted alongside the highway that typically bear the route number on the first line. The reference route system also includes parkways and other named highways (such as the Inner Loop

Inner Loop (Rochester)

The Inner Loop is an expressway that encloses downtown Rochester, New York, in the United States. Although the expressway is a continuous loop, only the portion of the loop north of Interstate 490 is signed as the "Inner Loop"...

), which are given a reference route designation for inventory purposes.

Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 maintains a system of state highways separate from its signed state routes. The state highway system is only used in ODOT internal accounting and is not signed.

Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 maintains a set of minor routes, called quadrant routes, that are often not signed. Pennsylvania also maintains relocated signed routes, interchanges, wye connections, rest areas, and truck escape ramps as unsigned state highways.