Maize agriculture was practiced in the US Southwest slightly before 2000 BC, but had a negligible impact on population growth rates until it was coupled with other innovations in subsistence and social practice. These include the development or introduction of more productive landraces; the ability to successfully cultivate maize under a greater variety of conditions, with dry farming especially important; the addition of beans, squash, and eventually turkey to the diet; and what we infer to be the remapping of exchange networks and the development of efficient exchange strategies in first-millennium-AD villages. Our tabulations of the P(5-19) proportion emphasize the heartlands of the Chaco and Mesa Verde Anasazi (prehispanic Pueblo) populations. We find that this measure is somewhat affected by warfare in our region. Nevertheless, there is a strong identifiable Neolithic Demographic Transition signal in the US Southwest in the mid-first-millennium AD in most sub-regions, visible a few hundred years after the introduction of well-fired ceramic containers, and more or less contemporaneous with the first appearance of villages.