Few studies have addressed the demographic characteristics of dental practice sites including endodontic practice sites. This study investigated the demographic characteristics of endodontic practice sites in the United States. Demographic data and endodontic practices were organized by zip codes and analyzed using discriminant analysis. The demographic characteristics associated with zip codes that contained an endodontic practice were determined versus the characteristics of zip codes that did not contain an endodontic practice. The resulting model correctly classified 93.7% of the 30,171 zip code areas based upon the presence or absence of an endodontic practice. The variables most closely associated with a zip code containing an endodontic practice included: number of dental practices (nonendodontic), population size, percent of adult population with a college degree, size of employed population, projected population growth (2005 to 2010), percent of population over 64 years old, and median housing value.