Austin is the capital city of the U.S. state of Texas, as well as the seat and largest city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the 11th-most populous city in the United States, the fourth-most-populous city in Texas, the second-most-populous state capital city after Phoenix, Arizona, and the most populous state capital that is not also the most populous city in its state.