Southern Arizona was once described as a "sea of grass" extending across the four major valleys, the Sulphur Spring Valley, the San Pedro Valley, the San Simon Valley and the San Bernardino Valley. But today the majority of that land is covered with desert shrubs like mesquite, leaving little to none of the natural grasses that once dominated these valleys. By the late 1800s Americans were flocking to southern Arizona to take advantage of some of the lushest grasslands the United States had to offer. Yet today we can find very little of these grasslands remaining, and so the image of this once productive land has been long forgotten. This thesis/creative project takes an in-depth look at what the land in Cochise County, Arizona once was, what it has become, and what happened to cause these drastic changes. It looks at the four major theories as to what caused these changes. The first of which is the overgrazing of cattle through the cattle boom of the late 1800s. The second is the effect of climactic events like drought and an increase in aridity over time. The third is the encroachment of what was thought to be non-native mesquite, which choked out the natural grasses. And the fourth and final theory is that the overarching suppression of fire by settlers allowed desert shrubs to expand their ranges into the grasslands. Through historical records like newspaper articles, photo archives, land surveys, military travel journals, census data, weather records as well as prior research works and interviews with researchers, conservationists and ranchers, a history of these lands is presented to show the major turning points in the lands' use and determine what led to their deterioration.