Plains is a town in and the county seat of Yoakum County of western Texas, United States. The city's population was 1,355 at the 2020 census. Yoakum County is in the Texas High Plains Wine country. In 1905, W. J. Luna founded and named Plains. When Yoakum County was organized in 1907, Plains was designated the county seat. Following the discover…Plains is a town in and the county seat of Yoakum County of western Texas, United States. The city's population was 1,355 at the 2020 census. Yoakum County is in the Texas High Plains Wine country. In 1905, W. J. Luna founded and named Plains. When Yoakum County was organized in 1907, Plains was designated the county seat. Following the discovery of oil in 1936 the population has grown steadily.