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is a city in Lake County, South Dakota, United States. The population was 6,540 at the 2000 census. It is the county seat of Lake County and is home to Dakota State University.
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.
Madison has been assigned the ZIP code 57042 and the FIPS place code 40220.