US Route 178 runs in northwestern South Carolina and southern South Carolina, with a slight foray north into western North Carolina. The northern end is at Rosman, North Carolina, at US Route 64, about six miles from the border with South Carolina. US Route 178 heads south straight for that border, spending almost all of its time in South Carolina. It passes southward through Anderson and turns southeasterly through Greenwood, Saluda, and Orangeburg, staying southwest of Interstate 26. US Route 178 ends by converging with US Route 78 between Interstate 95 and the Charleston area, near the village of Ridgeville. US Route 178 manages to fall short of reaching Charleston, pass just to the west of Greenville, and pass southwest of Columbia; thus, it avoids reaching any of South Carolina's most prominent cities.