ABSTRACT
VILLAGE FARMERS SPREAD NORTHWARD INTO THE deserts of the U.S. Southwest and the Mexican Northwest from Mesoamerica over three millennia ago. The three major cultural traditions used different adaptations to farming in this arid region. The frontiers of farming expanded over time, but farming also spread beyond the margins of the major traditions, adopted by hunter-gatherers who made it work in even more unlikely environments. Farming later collapsed in many areas in the face of climate change, forcing widespread relocations and spawning new derivative cultures. Major tasks for archaeologists have been to determine when, how, and why farming was made to work in this environment, and why it was abandoned across so much of the region by 1200 CE.
