|Maintained by SCDOT|
|Length||17.61 mi (28.34 km)|
|West end||near Joanna|
|East end||in Whitmire|
SC 66 is a two-lane rural highway that travels 17.6 miles (28.3 km) from SC 56 to SC 72 in Whitmire. It connects to U.S. Route 76 (US 76) and Interstate 26 (I-26). Predominantly in the Sumter National Forest, it meanders through forest lands; in Whitmire, it takes a couple of turns before reaching SC 72 via Central Avenue, Park Street and Glenn Street.
SC 66 was established in 1934 as a new primary routing, traversing from SC 56 to US 76/SC 2 in Goldville (now Joanna). In 1941 or 1942, a second SC 66 was created, from SC 706 in Eisons Crossroads to the Newberry-Laurens county line. In 1948, the two sections of SC 66 were connected, and was also extended east into Whitmire replacing part of SC 706.
South Carolina Highway 706 (SC 706) was established in 1940 as a new primary routing from US 76/SC 2 in Jalapa to SC 7 in Whitmire. In 1948, SC 706 was decommissioned with its routing north of Eisons Crossroads becoming part of SC 66, while south of it was downgraded to secondary Jalapa Road (S-36-32).
|Laurens||||0.00||0.00||- Chappells, Saluda, Clinton|
|Joanna||2.73||4.39||(Main Street) - Newberry, Clinton|
|- Columbia, Spartanburg||I-26 exit 60|
|Newberry||Whitmire||17.61||28.34||(Church Street) - Chester, Clinton|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|