Of the 3 major factors (habitat loss, poisoning, and disease) that limit abundance of prairie dogs today, sylvatic plague caused by Yersinia pestis is the I factor that is beyond human control. Plague epizootics frequently kill > 99% of prairie dogs in infected colonies. Although epizootics of sylvatic plague occur throughout most of the range of prairie dogs in the United States and are well described, long-term maintenance of plague in enzootic rodent species is not well documented or understood. We review dynamics of plague in white-tailed (Cynomys leucurus), Gunnison's (C gunnisoni), and black-tailed (C ludovicianus) prairie dogs, and their rodent and flea associates. We use epidemiologic concepts to support an enzootic hypothesis [...]