|Maintained by SCDOT|
|Length||14.52 mi (23.37 km)|
|South end||near McBee|
|North end||at the North Carolina line near Mount Croghan|
SC 109 was established in either 1937 or 1938 as a new primary route from SC 9 in Mount Croghan to the North Carolina state line. In 1939, it was extended south to SC 85. In 1941 or 1942, SC 109 was extended south again to U.S. Route 15 (US 15) in Hartsville; there was also a four-mile (6.4 km) separate piece connecting SC 155 to US 52. In 1948, SC 109 moved back to its current southern terminus at SC 145; both the former extension and separate piece were downgraded to secondary roads.
The entire route is in Chesterfield County.
|||0.00||0.00||/ Hartsville-Ruby Road - McBee, Chesterfield, Hartsville|
|Ruby||6.80||10.94||- Jefferson, Chesterfield|
|8.16||13.13||south (Main Street) / Market Street - Chesterfield||South end of SC 9 overlap|
|Mount Croghan||11.31||18.20||north (Main Street) / south (Depot Street) - Pageland, Jefferson||North end of SC 9 overlap; northern terminus of SC 268|
|||14.52||23.37||north - Wadesboro||North Carolina state line|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|