NC 55 is a 192-mile (309 km) North Carolina state highway that serves as a traffic artery connecting Durham with Cary and numerous small cities and towns in the The Triangle on its way toward the Pamlico Sound. A portion of NC 55 extends through Research Triangle Park. NC 55 is a major artery in the central part of The Triangle region, and is a four lane, divided highway between Durham and Cary and Apex. NC 55 is also a divided highway between Apex and Fuquay-Varina.

Although NC 55 is signed east–west, the most used section of road actually runs in a north–south alignment. Between Durham and Erwin "east" is really southbound and "west" is really northbound.

Starting at the northern terminus from US 501 Business (North Roxboro Street) near the concurrent I-85, US 15 and US 70, the highway passes through North Carolina Central University and then cuts a path through a fairly urbanized section of Durham. As it exits Durham, NC 55 widens to a four lane divided highway as it passes through the western side of Research Triangle Park. The next leg of the journey enters Cary and Apex. Extensive reconstruction of the roadway in this area, widened in anticipation of higher traffic volumes from NC-540 and construction in Apex and Cary, was completed in 2007. NC 55 is a major highway in western Wake County and is a direct link connecting the Triangle cities of Durham and Cary via the Research Triangle Park.

After the junction with US 64 and a few shopping-centers, NC 55 narrows as it passes through Apex (Williams St). After the junction with U.S. 1, NC 55 widens again and splits into business and bypass routes in Holly Springs. Finally, it proceeds to an open landscape with scattered sections of dense forest for the stretch towards Fuquay-Varina. The highway continues southeastward across US 401, eventually exiting Wake County into Harnett County.

In the Erwin/Dunn area the road heads east and merges with NC 50 in Newton Grove. NC 55 leaves to take a more easterly course towards the coast, ending at the Pamlico Sound in Oriental.