Amarillo is the 14th-largest city in the state of Texas, the largest in the Texas Panhandle, and the seat of Potter County. A portion of the city extends into Randall County. The population was 173,627 at the 2000 census. The Amarillo metropolitan area has an estimated population of 236,113 in four counties. In July 2009, the population was estimated at 189,389. In 1913, Amarillo became the first Texas city and the fifth in United States to use the council-manager form of municipal government, with all governmental powers resting in a legislative body called a commission. Amarillo's commission is composed of five elected commissioners, one of whom is the mayor of the city. The mayor and each commissioner serves a two-year term. The role of the commission is to pass ordinances and resolutions, adopt regulations, and appoint city officials, including the city manager. While the mayor serves as a presiding officer of the commission, the city manager is the administrative head of the municipal government, and is responsible for the administration of all departments. The city commission holds its regular meetings on Tuesday of each week.