The route was part of the
1926 approved plan for a national system of highways and appears on the approved map. When first signed, US 17 followed a route that went through Florence and Marion. The original route through South Carolina was long. At the time, U.S. Highways in South Carolina used a dual-numbering system; US 17 was also signed
SC 1 from Georgia to
Yemassee,
SC 30 from Yemassee to
Walterboro,
SC 6 from Walterboro to Charleston,
SC 2 from Charleston to
Goose Creek,
SC 41 from Goose Creek to
Florence,
SC 3 from Florence to North Carolina. By 1928, all the dual numbers had been removed except for SC 2. The entire route from Georgia to North Carolina was paved by 1930. At one point, the route from
Green Pond to Jacksonboro was SC 32. In 1931, the route was extended to Punta Gorda. The early routing was already identified to be shifted to the King's Highway which would pass through Myrtle Beach and Georgetown; rerouting occurred in 1935. In 1947, US 17 was relocated to stay onto King Street and Columbus Street in Charleston. In 1952, a one-way pair was created in Charleston near the Ashley River Bridge. By 1959, this had been modified again to use Spring Street. This one was officially named the T. Allen Legare Bridge. In 1963, the segment of roadway between Myrtle Beach and Atlantic Beach was widened to four lanes. The first tourist welcome center in South Carolina opened in February 1968 on US 17 near Little River. In December 1968, the segment of roadway in Downtown Charleston was moved off of local streets and onto the Crosstown Expressway. A segment of US 17 between Ridgeland and Point South once contained two four-lane divided sections. The first is in
Coosawhatchie between north of the culvert for Little Bees Creek and north of the bridge over the
Coosawhatchie River. From 1971 to 1975, portions of the segment were relocated onto
I-95. The divided section in Coosawhatchie remains intact, while the northbound lane near the Tullifinny wetlands was closed, and today is used for a fishing pier, a parking lot of a church, and a private home. In 1980, the road was widened to four lanes between Awendaw and McLellanville. In 1981, a bypass of Myrtle Beach was opened, US 17 Business was designated in its former place. it involved constructing new roadways, as well as utilizing existing roadways. In 1997, US 17 was rerouted to cross the Georgia state line through Savannah, this new segment replaced US 17 Alt. The old route into Georgia became part of an extended SC 170. In 2005, the Crosstown Expressway segment concurrent with Lee Street was permanently closed. In its place, a new concurrency with I-26 was created, and a new Meeting Street interchange was also constructed. This was done as part of a project to replace the obsolete Cooper River bridges. On April 21, 2010, the Crosstown Expressway was renamed the Septa Clark Expressway.
ACE Basin widening project The widening project addressed a 22-mile segment of the highway stretching from Gardens Corner in
Beaufort County to
Jacksonboro in
Colleton County. This segment of the road, notorious for its high accident rate, was featured on an
NBC Dateline special titled ''America's Most Dangerous Roads.'' In 1985, the
South Carolina Department of Transportation (SCDOT) recognized the need to improve the segment of US 17 due to substantial capacity and safety concerns. The project faced delays due to environmental challenges. Between 1997 and 2005, the segment experienced nearly 1,000 crashes, including 33 fatalities. The project widened the two-lane roadway to a four-lane highway, incorporating a grass median. Improvements included enhanced roadway alignments, bridge replacements, and upgraded intersections. Notably, the US 17/US 21 intersection was converted into a
diamond interchange featuring a
roundabout. The total estimated cost for the project was $173.4 million. ==Highway names==