Austin is the capital of the U.S. state of Texas and the county seat and most populous city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the 26th-largest metropolitan area in the United States, the 11th-most populous city in the United States, the fourth-most populous city in the state after Houston, San Antonio, and Dallas, and the second-most populous state capital city after Phoenix, the capital of Arizona.