Unsigned highway

An unsigned highway is a highway (most often a state highway) that does not bear conventional road markings. Depending on the state department of transportation involved, the route may instead be signed with small inventory markers for internal use, or nothing at all.

Routes are often left unsigned when they are extremely short. Possible motorist confusion may also be a factor, stemming from a similar highway number elsewhere in the system, or on a stretch of highway with many concurrencies, as in the case of Interstate 444 in Tulsa, Oklahoma and Interstate 345 in Dallas, Texas.

Highways running through parks and wildlife refuges can sometimes also be unsigned. U.S. Route 20 through Yellowstone National Park is an example.

Examples of entire unsigned route systems

The C, D, and U road systems in the Great Britain road numbering scheme are systems of routes considered less important than B roads and typically left unsigned.

Alaska and Puerto Rico have Interstate Highways for funding reasons, but they are not signed as such.

Florida assigns all U.S. and Interstate Highways a state route number which is usually not signed. An example is Interstate 4 being also assigned State Road 400, which is not shown on signs until after I-4 ends.

In New York, unsigned highways are most often reference routes, state highways that are signed only with reference markers, small green signs that bear the route number on the first line. The reference route system also includes parkways, which are given a number only shown on reference markers.

Oregon 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's unsigned routes are mostly quadrant routes, with numbers ranging from 1000 to 4999. Pennsylvania also maintains relocated signed routes, interchanges, wye connections, rest areas, and truck escape ramps as unsigned state highways.