Armour is a city in county seat of Douglas County, South Dakota, United States. The population was 698 at the 2020 census.

Douglas County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 2,835. Its county seat is Armour. The county was established in 1873 and organized in 1882. It is named for Stephen Douglas, Illinois political figure.