Wikipedia says, "Dallas is home to the third largest concentration of Fortune 500 companies in the nation. Located in North Texas and a major city in the American South, Dallas is the main core of the largest inland metropolitan area in the United States that lacks any navigable link to the sea. The city's prominence arose from its historical importance as a center for the oil and cotton industries, and its position along numerous railroad lines. Dallas developed a strong industrial and financial sector, and a major inland port, due largely to the presence of Dallas/Fort Worth International Airport, one of the largest and busiest airports in the world."