The Hohokam

The original 400,000 Arizonans . . . were, for the most part, members of the Hohokam culture, a civilization that thrived uninterrupted near the confluence of the Gila, Salt, and Verde rivers for at least a thousand years, until about 1400, when it disappeared. . . . [The Hohokam] were the first purely agricultural culture in the Southwest, if not all of North America. . . .

The Hohokam, by A.D. 800, had already established a civilization that rivaled the Aztec, Inca, and Maya farther south. They were good builders, using rafters for houses and I-beams to create ancestral skyscrapers four stories high. . . .

When it came to irrigation, however, the Hohokam were in a league by themselves. The largest of the canals they dug was fifteen miles long and eleven yards wide from bank to bank; like the other main canals, it had a perfectly calibrated drop of 2.5 meters per mile, enough to sustain a flow rate that would flush out most of the unwanted silt. There were dozens of miles of laterals and ditches, implying irrigation of many thousands of acres of land. Because of the dry climate and the provenance of the irrigated land, the Hohokam should have enjoyed good health; they made superior weapons; they were more populous than any culture around. Why then should they disappear? It is hard to imagine a civilization covering thousands of square miles and comprising hundreds of thousands of people just vanishing. . . .

Drought remains a possibility--perhaps a twenty-year drought the likes of which they had never seen--but an equally plausible explanation is that they irrigated too much and waterlogged the land, leading to intractable problems with salt buildup in the soil, which would have poisoned the crops. In either case, the mysterious disappearance of Hohokam civilizations seems linked to water: they either had too little or used too much.

^{Source: Reisner, Marc. Cadillac Desert: The American West and Its Disappearing Water. New York: Penguin Books, 1993. 255-257.}