Road number

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A road number is often assigned to a stretch of public roadway. The number chosen is often dependant on the type of road, with numbers differentiating between interstates, motorways, arterial throughfares, two-lane roads, and so forth.

In some countries, such as the United Kingdom, the number usually has a letter followed by a number of up to 4 digits. For example, the main road from London to Edinburgh is called the A1, the "A" in Britain indicating a first class route; this is classified as being more important than "B" roads.

In other countries, such as the United States, the situation is a bit more complicated. The numbers can be broken up into several major classifications, such as Interstate highways, or high-speed limited-access highways. For instance, the interstate between Boston and Seattle is called Interstate 90. The United States highways are often more local routes that can span multiple states and can include multiple roadway classifications. An example of this is the U.S. highway linking Maine to Florida called U.S. Route 1. There are also state highways, or roadways under the control of the state government and are usually more minor than those of U.S. highways. These are often titled with the state name followed by the route number; Kentucky state highway 67 indicates a Kentucky state road numbered 67.

The numbering system for state highways varies widely from state to state. A state may choose to use letter prefixes for all, some, or none of its state roads. For example, the Virginia Department of Transportation does not use letter prefixes for state primary or secondary routes, but does use an "F" prefix for frontage roads. Although the state's two-letter designation usually becomes a prefix for the route, some states, like Michigan, prefer to use a single-letter prefix (such as "M-28"). Indeed, a state may choose to give a route an entirely alphabetic designation, such as the lettered county routes in Missouri and Wisconsin.

Some routes may carry a letter suffix, such as E/W (for East/West) or N/S (for North/South). Other lesser-known suffixes include A (for Alternate), B (for Business) and C (for City).

Complicating the issue further is the fact that some states have distinct numbering systems for primary and secondary routes or for state routes and county roads. For example, in Virginia, the primary and secondary road systems have numbering ranges that are, with rare exceptions, mutually exclusive.

Certain fictional road numbers have been set aside for use in TV shows or films.

France still uses Route Nationale numbers from an 1824 revision of 1811 numbers made under Napoleon.

Road number

See also

Further reading