In South Carolina the maximum speed limit of 70 mph (113 km/h) is posted on interstates. Interstates passing through urban areas are dropped to 60 mph (97 km/h). The urban area assignment of 60 mph (97 km/h) usually includes the metropolitan area and the actual inner city area. The two exceptions to the rule are the SC 31 freeway around Myrtle Beach and I-95 around Florence. SC 31 is posted at 65 mph (105 km/h) even though it is in the greater Myrtle Beach area. I-95 even as a 6 lane semi-urban built freeway, maintains a 70 mph (113 km/h) speed limit through the Florence area, from just south of exit 160 to just south of exit 164, the speed limit is reduced to 60 mph (97 km/h).
Four-lane arterials by default are posted at 60 mph (97 km/h). Four-lane bypasses posted at 60 mph (97 km/h) can be found in Marion and Sumter, but others remain at 55 mph (89 km/h). It is not uncommon that 55 mph (89 km/h) can be expected in more built-up areas prior to municipalities and/or if the engineering on the highway is below standards.
Two-lane roads have a 55 mph (89 km/h) speed limit by default. However, a handful of counties maintained as either state secondary roads or county roads are posted at 45 mph (72 km/h).
Central business districts (CBDs) are posted at 30 mph (48 km/h) to 25 mph (40 km/h).
Speed limit drops generally are done in 10 mph (16 km/h) increments but 20 mph (32 km/h) increments are not uncommon. The speed limit drops from 55 mph (89 km/h) to 25 mph (40 km/h) at a traffic circle with US 378 and SC 391 in eastern Saluda County. On US 52 northbound approaching Kingstree, the speed limit drops from 60 mph (97 km/h) to 35 mph (56 km/h).