Phoenix is known as the "Valley of the Sun," while Tucson is referred to as "The Old Pueblo." These nicknames epitomize the difference in the public's perception of each city. Phoenix continues to sprawl as one of America's largest and fastest-growing cities. Tucson has witnessed a slower rate of growth, and has only one quarter of Phoenix's population. This was not always the case. Prior to 1920, Tucson had a larger population. How did two cities,...