Selma is a city in Bexar, Comal, and Guadalupe counties in the U.S. state of Texas. It is part of the San Antonio Metropolitan Statistical Area. The population was 5,540 at the 2010 census, up from 788 at the 2000 census.The Retama Park horse racing track is located in Selma.The town was famous as a speed trap as referenced in the Steve Earle song "Guitar Town".