SC 641 appears south of Lodge 1930 Official

SC 641 extended to Sycamore 1938 Official

In 1942, SC 641 was straightened out in southern Bamberg County to its current routing. The old route became part of SC 330 (now S-5-31) and SC 643 (now S-3-8 and S-5-8).

SC 641 loops around 1940 Official

SC 641 straight through 1942 Official

In 1947, SC 641 was extended west to US 301 Allendale, replacing a part of SC 73.
In 1953, SC 641 was extended west with US 301, then replaced some of SC 28 to end at the southeastern boundary of the Savannah River Site just inside Barnwell County.
About 1957, SC 641 was removed from what is now a 1.5 mile unpaved road west from Kearse Rd (west of Jackson Branch near Sycamore)
In 1968 or 1969, SC 641 was truncated back to US 301 Allendale, replaced by SC 125 which became driveable through the Savannah River Plant.

SC 641 extended to Allendale 1948 Official

SC 641 extended to Savannah River Plant 1953 Official

SC 641 truncated to Allendale 1969 Official

Improvements: SC 641 was paved from SC 64 to SC 36 in 1932.
The rest of SC 641 was paved in 1941.
SC 641 was multilaned on its US 301 overlay starting in 1963; no current multilane segments.
Comment: SC 641 makes an empty but fine short cut to travel from Augusta to Charleston via SC 125-641-64....