With an estimated population of 1,,,  it is the ninth most-populous city in the U. Dallas and nearby Fort Worth were 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. Dominant sectors of its diverse economy include defense , financial services , information technology , telecommunications , and transportation. Preceded by thousands of years of varying cultures , the Caddo people inhabited the Dallas area before Spanish colonists claimed the territory of Texas in the 18th century as a part of the Viceroyalty of New Spain. Later, France also claimed the area but never established much settlement.