Dermacentor parumapertus Neumann is an ixodid tick distributed broadly across arid and semi-arid regions of the western United States and northern Mexico. D. parumapertus has garnered little attention by most medical entomologists due predominantly to historical assumptions that it fed almost exclusively on lagomorphs. We summarized data from multiple sources to provide a comprehensive and current description of the distribution, host records, and Rickettsia species associated with this understudied species of potential medical importance. By using historical and recent scientific literature, natural history museum records, and archival collection records from the US National Tick Collection and the US Department of Agriculture (USDA)-National Veterinary Services Laboratories, we compiled county- and municipality-level locality records for D. parumapertus from 119 counties in 14 US states, and 12 municipalities in 10 states in Mexico. We further identified host records for nymphs and adults of D. parumapertus from 52 vertebrate species. From 199 field-collected adult D. parumapertus, we detected DNA of Rickettsia bellii, Rickettsia rhipicephali, and the potentially pathogenic Rickettsia parkeri Black Gap genotype in 61.3%, 4.5%, and 4.0% of the total specimens, respectively. From these data and information acquired from historical and recent scientific literature, we identified the occurrence of R. parkeri-infected D. parumapertus from 10 counties in 6 US states, and 2 municipalities in 2 states in Mexico. Collectively, these findings indicate broad distribution of D. parumapertus in western North America, a broader range of hosts than summarized previously, and association of this tick with a potential pathogen in several US states and municipalities of Mexico.