We examined spatial distributions and resource partitioning among female mule deer (Odocoileus hemionus) and female North American elk (Cervus elaphus) during summer and winter in southeastern Idaho, USA. Our objective was to understand differences in distributions and habitat selection by these two species of large herbivores in a sagebrush-steppe ecosystem. We used multi-response permutation procedures to examine seasonal distributions of mule deer and elk. We compared animal locations with random locations on a GIS-based habitat map to examine habitat selection and importance. Both species were more widely distributed during summer than winter, when distributions of both species were more restricted. During winter, habitat selection differed among mule deer and elk in use of aspect; east facing slopes were selected by elk and west-facing slopes by mule deer. Mule deer also were located closer to roads than random locations, which may have resulted from avoidance of elk. We observed no differences in habitat selection between mule deer and elk during summer, although these large herbivores showed resource separation by strongly partitioning use of habitats. Conversely, both species used the shrub-steppe ecosystem during winter, but partitioned habitat mostly via use of aspect and distance to roads. Our research provides insights into niche partitioning between these large mammals.