1860, December 20 South Carolina, rapidly followed by six other southern states, secedes from Union in reaction to election of Lincoln, who opposes extension of slavery into western territories. These states organize the Confederate States of America.
St. Mary County Louisiana (Vacant / Not In Use) has 1 places on the National Register of Historic Places including 1 place of Statewide significance. Significant places include Southwest Reef Lighthouse. Prominent architectural styles found in St. Mary Country are .