Clark is a city in Clark County, South Dakota, United States. The population was 1,139 at the 2010 census. It is the county seat of Clark County.
Clark is located at 44°52′46″N 97°44′3″W / 44.87944°N 97.73417°W / 44.87944; -97.73417 (44.879459, -97.734182).
According to the United States Census Bureau, the city has a total area of 1.3 square miles (3.4 km²), all of it land.