South Carolina Specific:

SC National Register – Static, no updates in years

SC Historical Properties Search
SC Department of Archives and History

WPA Survey – Church Form
WPA sponsored survey around 1936 of South Carolina churches. Hosted by USC.

Sanborn Fire Maps of SC
Hosted by USC.

SC Picture Project
Many towns, plantations, and homes are documented here. This is a non-profit run website with curated user-submitted photos and histories.