Dallas (/ˈdæləs/) is a city in the U.S. state of Texas and the most populous city in the Dallas–Fort Worth metroplex, the most populous metropolitan area in Texas and the 4th most populous metropolitan area in the United States at 7.5 million people. It is the most populous city in and seat of Dallas County with portions extending into Collin, Denton, Kaufman, and Rockwall counties. With a 2020 census population of 1,304,379, it is the ninth-most populous city in the U.S. and the third-most populous city in Texas after Houston and San Antonio. Located in the North Texas region, the city of 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.[a]
Dallas and nearby Fort Worth were initially developed as a product of the construction of major railroad lines through the area allowing access to cotton, cattle, and later oil in North and East Texas. The construction of the Interstate Highway System reinforced Dallas's prominence as a transportation hub, with four major interstate highways converging in the city and a fifth interstate loop around it. Dallas then developed as a strong industrial and financial center and a major inland port, due to the convergence of major railroad lines, interstate highways and the construction of Dallas/Fort Worth International Airport, one of the largest and busiest airports in the world. In addition, Dallas Area Rapid Transit (DART) operates rail and bus transit service throughout the city and its surrounding suburbs.