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 nearly 10,000 acres were listed for sale in Travis County recently, representing a total value of almost $1 billion in Travis County land and rural real estate for sale. Travis County ranks 27th in the Lone Star State for the combined amount of land currently advertised for sale. There were four properties listed as sold in Travis County through the Land Network Comparable Sales Program. This represented a total value of $10,385,000. Of all farms, ranches, and rural real estate for sale in Travis County, Austin had the most land for sale. From an economic perspective, government and state-level services contribute most to Travis County's overall GDP. Travis County is Texas's 75th largest county (1,023 square miles). It's located in the Blacklands South Texas region of Texas.