Thomas is a city in Custer County, Oklahoma, United States. The population was 1,181 at the 2010 census. Thomas was named for Wi…Thomas is a city in Custer County, Oklahoma, United States. The population was 1,181 at the 2010 census. Thomas was named for William Thomas, who owned a general store and served as postmaster, when the first post office was established at the store on February 12, 1894, while this area was part of Oklahoma Territory. Joseph W. Morris claimed a homestead at the site during the Cheyenne-Arapaho opening in 1892. The Oklahoma Railway Townsite platted Morris' land in 1902, the same year that the Blackwell, Enid and Southwestern Railroad constructed a line through Thomas. In 1906, the Kansas City, Mexico and Orient Railway also built a line through the town. Most of the early settlers were members of the Amish, the Dunkards, and the Church of the United Brethren in Christ religious groups.