Sarcoptic mange epidemics erupted in two of the remaining populations of endangered San Joaquin kit foxes (Vulpes macrotis mutica). Both populations are in urban habitats in the cities of Bakersfield and Taft, California, USA. The risk of disease spread from the two urban populations to nearby nonurban populations, and then throughout the species range, is of considerable conservation concern. To date, mange has not been detected in any nonurban populations despite considerable surveillance effort. The reasons for the lack of detections of mange among nonurban foxes are unknown. We monitored urban kit fox movements using geographic positioning system (GPS) collars to test the hypothesis that urban foxes were not venturing into nonurban habitats. Of 24 foxes monitored December 2018 to November 2019, 19 (79%) made excursions from urban into nonurban habitats from 1–124 times. The mean number of excursions per 30 d was 5.5 (range 0.1–13.9 d). The mean proportion of locations in nonurban habitats was 29.0% (range 0.6–99.7%). The mean maximum distance that foxes traveled into nonurban areas from the urban-nonurban interface was 1.1 km (range 0.1–2.9 km). Mean number of excursions, proportion of nonurban locations, and maximum distance into nonurban habitats were similar between Bakersfield and Taft, females and males, and adults and juveniles. At least eight foxes apparently used dens in nonurban habitats; shared use of dens may be an important mode of mange mite transmission between conspecifics. Two of the collared foxes died of mange during the study and two others had mange when captured at the end of the study. Three of these four foxes had made excursions into nonurban habitats. These results confirm a significant potential for mange to spread from urban to nonurban kit fox populations. We recommend continued surveillance in nonurban populations and continued treatment efforts in the affected urban populations.