SC 33 ALT #1: Appeared 1936 or 1937 as new primary routing running from US 17 to SC 33 (now SC 46) west of Hardeeville.
In 1939, SC 33 ALT was renumbered as SC 5. Today it is part of US 321.
SC 33 ALT #2: Appeared 1936 or 1937 as a renumbering of mainline SC 33, running from SC 33 (now S-7-13) Bluffton south to the nearby May River waterfront.
In 1939, SC 33 ALT was renumbered as SC 46 ALT (now S-7-66 and S-7-31).