Austin,_Texas | isPartOf | Hays_County,_Texas Hays_County,_Texas | largestCity | San_Marcos,_Texas Austin,_Texas | isPartOf | Williamson_County,_Texas Williamson_County,_Texas | countySeat | Georgetown,_Texas
Austin, Texas is part of Williamson County, which has the county seat of Georgetown. It is also included in Hays County where the largest city is San Marcos.