Amarillo is a city in the U.S. state of Texas and the seat of Potter County. It is the 14th-most populous city in Texas and the most populous city i…Amarillo is a city in the U.S. state of Texas and the seat of Potter County. It is the 14th-most populous city in Texas and the most populous city in the Texas panhandle. A portion of the city extends into Randall County. The estimated population of Amarillo was 200,393 as of April 1, 2020, comprising nearly half of the population of the panhandle. The Amarillo metropolitan area had an estimated population of 308,297 as of 2020.