Austin (/ˈɒstɪn, ˈɔː-/ ( listen),AWST-in) is the capital of the U.S. state of Texas and the seat of Travis County, with portions extending into Hays and Williamson counties. It is the 11th-most populous city in the United States and the 4th-most populous city in Texas. It is the fastest growing large city in the United States and the second most populous state capital in the U.S after Phoenix, Arizona. As of the U.S. Census Bureau's July 1, 2016 estimate, Austin has a population of 947,890. Located in Central Texas in the foothills of Texas Hill Country, the city is home to numerous lakes, rivers, and waterways including Lady Bird Lake, Barton Springs, McKinney Falls, the Colorado River, Lake Travis, and Lake Walter E. Long. It is the cultural and economic center of the Austin–Round Rock metropolitan statistical area, which had an estimated population of 2,056,405 as of July 1, 2016. It is the most populous state capital in the United States that isn't the most populous city in a state.