San Angelo ( SAN AN-jə-loh) is a city in and the county seat of Tom Green County, Texas, United States. Its location is in the Concho Valley, a region of West Texas between the Permian Basin to the northwest, Chihuahuan Desert to the southwest, Osage Plains to the northeast, and Central Texas to the southeast. According to the 2020 United States Census, San Angelo had a total population of 99,893. It is the principal city and center of the San Angelo metropolitan area, which had a population of 121,516. San Angelo is home to Angelo State University, historic Fort Concho, and Goodfellow Air Force Base. It is the seat of the Roman Catholic Diocese of San Angelo.