Wilmot is a city in Roberts County, South Dakota, United States. The population was 432 at the 2020 census. Wilmot, as well as Brookings…Wilmot is a city in Roberts County, South Dakota, United States. The population was 432 at the 2020 census. Wilmot, as well as Brookings, were named for Wilmot Brookings, who was provisional governor of the Dakota Territory.