This document identifies and maps high-density squatter settlements around Mexico City using population density gradients. It analyzes population density data from 2000 to show that density generally decreases with distance from downtown, but some municipalities over 15 miles out have even higher densities. These outliers are revealed to be impoverished squatter settlements lacking proper infrastructure. The characteristics of these peripheral settlements follow the Latin American model of urban development, where socioeconomic status decreases inversely with distance from the central business district, unlike the North American model.