Texas County is a county located in the panhandle of the U.S. state of Oklahoma. Its county seat is Guymon. As of the 2010 census, the population was 20,640. 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. It is one of the top-producing counties in the U.S. for wheat, cattle, and hogs. It also lies within the noted Hugoton-Panhandle natural gas field.