Custer County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 4,704. The county seat is Westcliffe. Custer County was created by the Colorado legislature on March 9, 1877, out of the southern half of Fremont County. It was named in honor of Lt. Colonel George Armstrong Custer, who had died the previous year. …Custer County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 4,704. The county seat is Westcliffe. Custer County was created by the Colorado legislature on March 9, 1877, out of the southern half of Fremont County. It was named in honor of Lt. Colonel George Armstrong Custer, who had died the previous year. Originally set in Ula, the county seat moved to Rosita in 1878, and to Silver Cliff in 1886 before settling in Westcliffe in 1928.