| 1939 – present|
| 31.1 km|
| US 17 Alt. near Summerville|
US 52 / US 78 in North Charleston
Charleston County, South Carolina, Dorchester County, South Carolina
South Carolina Highway 642 (SC 642, also known as Dorchester Road), is a 19.3-mile-long (31.1 km) state highway in the southeastern part of the U.S. state of South Carolina. It travels within the North Charleston and Summerville areas.
South Carolina Highway 642 Wikipedia
SR 642 runs for 19.3 miles (31.1 km) from US 17 Alternate southwest of Summerville to US 52/US 78 in North Charleston. Dorchester Road is a heavily congested highway during morning and evening traffic periods. In Summerville, it narrows to a two lane road, creating a bottleneck of traffic in Dorchester County.