The Phoenix area had no sizable Mexican presence before the U.S. took over the territory. Some assumed that the region was founded completely by whites from the outset. Whites and Mexicans actually held nearly equal populations throughout the first two decades of settlement. Though they did not hold equal status, their cohabitation was largely characterized by mutual interdependence and respect. Transforming the Salt River Valley's desert terrain into a regional agricultural hub depended on the Sonorans' preindustrial skills. As the town modernized, a new class of resident sought large scale projects to integrate Phoenix into the U.S. economy. Two pivotal projects achieved this. First, railroad spur lines made Phoenix accessible for migrants, as well as allowing farmers to supply commercial markets profitably. Second, the massive Roosevelt Dam secured a stable water supply for valley farmers. While these projects provided the foundation for development, it was cotton that brought commercial success. Throughout World War I, valley cotton growers capitalized on the booming cotton market by expanding their average acreage from 400 acres in 1912 to 130,000 acres in 1920. This rapid escalation to meet wartime demands depended upon a massive seasonal labor force from Mexico. While this boom brought prosperity to valley farmers, it solidified the Mexican's role in the Salt River Valley as little more than a laborer. Valley cotton growers impressively managed all labor issues through a well-organized collective association. Over-recruitment and wage setting kept workers from collective bargaining for better wages. The cotton growers' hegemony crashed along with cotton prices in 1921. Though the industry recovered fairly quickly, the cotton growers faced a new challenge in the rising national clamor to restrict Mexican immigration to the U.S. Though growers fought restrictions in Congressional hearings throughout the decade, the economic crash of 1929 finally ended widespread Mexican immigration. By the time of the crash, most Mexicans who remained lived in the agricultural peripheries or scattered urban barrios.