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.
Dallas and nearby Fort Worth initially developed due to 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.Dallas is rated a "beta(+)" global city. The economy of Dallas is considered diverse, with dominant sectors including defense, financial services, information technology, telecommunications, and transportation. It serves as the headquarters for 9 Fortune 500 companies within the city limits. The Dallas–Fort Worth metroplex hosts additional Fortune 500 companies, including American Airlines (Fort Worth), ExxonMobil (Irving), and J.C. Penney (Plano). The city has a population from a myriad of ethnic and religious backgrounds and the sixth-largest LGBT population in the United States.