SC 51 ALT #1: Appeared Nov 1936 as new BELT primary routing running as a short loop off SC 51 in Pamlico using Main St, Trade St, and 3rd Ave.
In 1947, SC 51 ALT was downgraded to S-21-21. Today, Main St is not state maintained; Trade St is S-21-119; 3rd Ave is still S-21-21.