Dallas continued to grow during the Reconstruction years, unlike many Southern towns that still had the task of major rebuilding at hand. By this time, Dallas had also become the center of the buffalo market. In 1871, Dallas legally became a city.he major north-south and east-west Texas railroad routes intersected in Dallas in 1873, thus ensuring its future as a commercial center. The arrival of the trains also meant soaring populations — the population of Dallas shot from 3,000 in early 1872 to more than 7,000 in September of the same year.