Purcell is a city in and the county seat of McClain County, Oklahoma, United States. As of the 2020 census, the city population was 6,651, a 13% increase from 2010. Founded in 1887, Purcell was a railroad town named after Edward B. Purcell, who was an official with the Atchison, Topeka and Santa Fe Railway. Purcell is often called the "Quarterhorse Capital of the World" and its official motto is "Heart of Oklahoma." The city has registered trademarks on both titles.