Dallas is a city in the U.S. state of Texas. With an estimated 2017 population of 1,341,075, it is the ninth most-populous city in the U.S. and third in Texas after Houston and San Antonio. Dallas is the main core of the largest metropolitan area in the Southern United States and the largest inland metropolitan area in the U.S. that lacks any navigable link to the sea. It is the most populous city in the Dallas–Fort Worth metroplex, the fourth-largest metropolitan area in the country at 7.3 million people as of 2017. Dallas is the seat of Dallas County. Sections of the city extend into Collin, Denton, Kaufman, and Rockwall counties.