http://www.texastribune.org/2015/03/26/texas-counties-cities-among-fastest-growing-us/ Texas Counties, Metros Among Fastest-Growing in U.S.], Texas Tribune, March 26, 2015 The approximately 10000 sqmi region centers on Harris County, the third-most populous county in the U.S., which contains the city of Houston—the largest economic and cultural center of the South—with a population of 2.3 million. [