Post is a city in and the county seat of Garza County, Texas, United States. Its population was 4,790 at the 2020 census, and according t…Post is a city in and the county seat of Garza County, Texas, United States. Its population was 4,790 at the 2020 census, and according to 2023 census estimates, the city is estimated to have a population of 3,486. The Triassic reptile Postosuchus is named after the city.