Primary highways are marked by a black square sign in which is a white equilateral diamond shape with rounded corners that contains the route number.

Other times, as in NC 295, the number is a place holder for when the highway is eventually upgraded to an Interstate route when it meets certain standards.

For example, Rustic Court is a very short road, barely one tenth of a mile in length; yet, it crosses the Durham-Orange county line.

The significance of secondary road numbers is almost exclusive to NCDOT operations, generally maintenance, rather than for navigational purposes by the driving public.

Rather, this is the job of the road names, which are generally established at the local level, but which often share a sign with an SR designation for convenience.

It is not uncommon for maintenance responsibility of secondary roads to transfer from NCDOT to particular municipalities as they increase in size due to annexation.

The SR road designation is also eliminated from physical roadways that are elevated into the primary system.

Although it ascended into the primary system years ago, some of the old signs identifying Guess Road as SR 1008 remain.

[6] These cross-state routes were used as a basis for numbering the two-digit roads that served as the major city-city connectors.

No effort has ever been made to match up with Tennessee or Georgia routes, but most cross-border numbered roads along this area are already U.S. highways anyway.