Southside is a census subdistrict (CSD) on Saint Thomas in the United States Virgin Islands. The CSD is bordering Charlotte Amalie from Havensight in the west, Nordside- and the Tutu subdistricts to the north, and the East End subdistrict to the east. The 2010 U.S. Census showed a population of 5,411 people, which is a decrease of 56 people as compared to the 2000 U.S. Census of 5,467. Some of the communities here includes Havensight, Bellevue, Raphune, Hoffman, Bolongo and Bovoni.

Saint Thomas is one of the Virgin Islands in the Caribbean Sea, and a constituent district of the United States Virgin Islands (USVI), an unincorporated territory of the United States. Along with surrounding minor islands, it is one of three county-equivalents in the USVI. Together with Saint John, it forms one of the districts of the USVI. The territorial capital and port of Charlotte Amalie is located on the island.