Hermosa is a town near the northern edge of Custer County, South Dakota, United States. The population was 382 at the 2020 census. Hermosa was developed by the Fremont, Elkhorn and Missouri Valley Railroad, later acquired by the Chicago and North Western Railway, and was platted in 1886. It was given its name, the Spanish for "beautiful"…Hermosa is a town near the northern edge of Custer County, South Dakota, United States. The population was 382 at the 2020 census. Hermosa was developed by the Fremont, Elkhorn and Missouri Valley Railroad, later acquired by the Chicago and North Western Railway, and was platted in 1886. It was given its name, the Spanish for "beautiful", for its views of the Black Hills and the grasslands; the railroad located it a mile uphill from an existing stagecoach stop. A post office has been in operation in Hermosa since 1886.