Texas County is a county located in the panhandle of the U.S. state of Oklahoma. Its county seat is Guymon. As of the 2020 census, the population was 21,384. It is the second largest county in Oklahoma, based on land area, and is named for Texas, the state that adjoins the county to its south. Texas County comprises the Guymon, OK Micropolitan Statistical Area. The county economy is largely based on farming and cattle production.