Madison is a city in Lake County, South Dakota, United States. The population was 6,474 at the 2010 census. It is the county seat of Lake County and is home to Dakota State University. Madison is located at 44°0′28″N 97°6′53″W / 44.00778°N 97.11472°W / 44.00778; -97.11472 (44.007734, -97.114738). According to the United States Census Bureau, the city has a total area of 4.3 square miles (11.1 km²), all of it land.