South Windsor is a town in Hartford County, Connecticut, United States. The population was 25,709 at the 2010 census. (Old) Main Street, located near the Connecticut River and running north to south from the border of East Hartford to that of East Windsor, is the center of the town's historical district. Wood Memorial Library, Ellsworth School, and the nation's oldest continually operating post office are located on the street. Minister Timothy Edwards is buried in a cemetery located on Main Street, and the town's middle school is named for him. In 1698, Edwards became the first minister for the settlers on the east side of the river and his church was built on Main Street (in present-day South Windsor). His son, theologian Jonathan Edwards, was born in South Windsor (at the time still part of Windsor). Ulysses S. Grant stayed at a home on the street. South Windsor is a town in Hartford County, Connecticut, United States. The population was 25,709 at the 2010 census.