Thomson, the county seat of McDuffie County, was incorporated as a village on February 15, 1854. The City of Thomson was once entirely owned by plantation owner John Langston. The city was named for Edgar Thomson of the Georgia Railroad.
The Old Rock House in Thomson, built in 1785, is said to be one of Georgia's oldest documented houses with design intact. Built by Thomas Ansley, the home is said to be the home of ancestors of former president Jimmy Carter.