The central region of Texas covers the state's three largest cities: Houston, Dallas-Fort Worth and San Antonio. The limestone terrain of Texas Hill Country lies in Central Texas, as do the state's three largest rivers, the Trinity, the Brazos and the Colorado. A total of approximately 100,000 acres were listed for sale in Williamson County, Texas, recently; the combined value of all Williamson County farms, ranches, hunting land and other land for sale was almost $1 billion. Williamson County ranks 50th in the state for the combined amount of land currently advertised for sale. Among cities in Williamson County with land and rural real estate for sale, Georgetown had the most land for sale. Williamson County is the 49th largest county (1,134 square miles) in Texas. It's located in the Blacklands South Texas region of the state.