National Highway System (Carolina)

The National Highway System of Carolina (often called National Routes or F.R.C. Highways) is an integrated network of roads and highways numbered within a nationwide grid in Carolina. 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 1918.

The route numbers and locations are coordinated by Federal Department of Transportation but are also usually in cooperation with the American Association of State Highway and Transportation Officials (AASHTO). Generally, north-to-south highways are odd-numbered, with lowest numbers in the Atlantic States, and highest in Cajiana. Similarly, east-to-west highways are typically even-numbered, with the lowest numbers in the north, and highest in the south. Major north–south routes have numbers ending in "1" while major east–west routes have numbers ending in "0". Three-digit numbered highways are spur routes of parent highways but are not necessarily connected to their parents. Some divided routes exist to provide two alignments for one route, even though many splits have been eliminated. Special routes, usually posted with a banner, can provide various routes, such as an alternate, bypass or business route, for a National Highway.

Before the National Routes were designated, auto trails were designated by states linking up the country. However states often did not cooperate on where the roads would be, therefore a main autotrail would turn into a dirt path once entering another state. In 1915 a committee of all eight state departments of transportation decided to create a new Federal Department of Transportation, whose main responsibility would be to maintain a new system of national highways among other things. In 1917 the first plan was produced, and in 1918 states had begin implementing the program. In 1956, Carolina decided to renumber it's National Highway System to match the numbering of routes running to the United States. The renumbering proposal was a contingency of Carolina joining into the Interstate Highway System.

Expansion of the system continued until 1956, when the Interstate Highway System was formed. After construction was completed, many National Routes were replaced by Interstate Highways for through traffic. Despite the Interstate system, National Highways still form many important regional connections, and new routes are still being added.