Cotton Hill, also known as Crow's Mill or Cotton Hill Post Office, was a small unincorporated community on the banks of Sugar Creek in Ball Township, Sangamon County, Illinois, about eight miles south of downtown Springfield. It stood for slightly over a century, from the 1820s until it was razed in the 1930s to make way for Lake Springfield. In 1900 the community had an estimated population of 150, a post office and a train station on the Illinois Central. Just before its demolition in the 1930s the community had a store, a schoolhouse, a blacksmith's shop, and a gas station on Route 66.

Lake Springfield is a 3,965-acre (16.05 km2) reservoir on the southeast edge of the city of Springfield, Illinois. It is 560 ft (170 m) above sea level. The lake was formed by building Spaulding Dam across Sugar Creek, a tributary of the Sangamon River. It is the largest municipally-owned body of water in Illinois. The lake and the lands adjoining it are all owned by City Water, Light & Power, the municipal utility for the city of Springfield, which operates the Dallman Power Plant at the lake's north end. Multiple city parks border its shores.