This article is a report on computerization and analysis of data collected during the Teotihuacan Mapping Project. The surface collection strategy and some of its weaknesses and strengths are discussed. The development, structure, and contents of the database, for which the author was primarily responsible, are also described in some detail. Essentially, it contains information on ceramic and lithic artifacts collected on more than 5000 separate tracts within the boundaries of the ancient city. The results presented consist of contour plots of sherd densities for the Cuanalan, Patlachique, Tzacualli, Xolalpan, and Metepec phases. These maps indicate where population was concentrated during each phase and, by extension, where significant population growth or shifts in population occurred between phases. The most important finding is that the population of the city during Patlichique times (Late Preclassic) was considerably greater than had been thought, and therefore that the period of explosive growth of the city began earlier than was thought. Corresponding to this observation, less drastic growth is suggested for subsequent phases.