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 Texas's Hamilton County recently; the overall value of all Hamilton County ranches, farms, hunting land and other rural land and acreage for sale was approximately $246 million. Hamilton County ranks 79th in the state for the total acreage of land currently advertised for sale. Hamilton featured the most land for sale. Agriculture and farming drives the Hamilton County economy, with 1,001 farms recorded in the county during the U.S. Census in 2012. Farming activities in Hamilton County generate annual revenues of $1 million, the majority of which comes from livestock products. Hamilton County is Texas's 195th biggest county (836 square miles). It's located in the Hill Country North Texas region of Texas.