General: B. idahoensis occurs throughout the Great Basin and neighbouring intermountain areas, in sagebrush habitat from southwestern Montana and western Wyoming in the east to southwestern Utah in the southeast and an isolated population in central Washington. The range also includes central Nevada to northeastern California, to the north in eastern Oregon and southern Idaho (Dobler and Dixon 1990). Within this wide range, it occurs in patches correlating positively to the density of sagebrush (Dobler and Dixon 1990).
Washington: B. idahoensis historically occurred in many areas of the Columbia Basin, but the sagebrush habitat has been heavily overgrazed and cleared completely for agriculture in many places. The population in Washington is now isolated from other populations (Dobler and Dixon 1990).
Idaho: Known populations of B. idahoensis are patchy but locally abundant in some areas within the valleys of the east-central region (Lemhi, Birch Creek, Big and Little Lost, and Pahsimeroi Valleys). Recently, isolated populations have been located in Owyhee County in the southwest of the state. Isolated populations also have been documented in the south-central region on the Camas Prairie (Rachlow 2004a).
An understanding of the current status and distribution of populations is limited by sampling effort; intensive surveys for populations have not been conducted in most areas. Within Idaho, agricultural and urban development of the Snake River Plains likely represents a significant barrier dividing populations north and south of the Snake River. Some populations north of the Snake River connect to those in southwestern Montana (including populations on the Continental Divide). South of the Snake River, populations likely connect to those in neighboring states (Oregon, Nevada, and Wyoming). The Idaho Conservation Data Center (IDCDC) has approximately 180 records of the species in the program's geospatial database, comprising both recent and historical records of occurrence. The World Conservation Union (IUCN) recommends that the area of occupancy be computed by overlaying the distribution of known occurrences with a uniform grid and tallying the area of occupied grid cells. Using a 2-km grid, we calculated the area of occupancy to be 748 km² using IDCDC records. Two important sites are the Idaho National Environmental and Engineering Laboratory (INEEL) and the Lemhi Valley, BLM lands south of Salmon, Idaho. Both areas have received significant research currently or in the past, and both support large populations of pygmy rabbits (Dixon and Bosworth 2004).
Wyoming: B. idahoensis in Wyoming appears to be widespread throughout the sagebrush-dominated portions of the Bear and Green River Basins. In the Bear River, B. idahoensis is consistently found in good numbers at Fossil Butte National Monument. In the Green River, B. idahoensis is consistently found to the south and west of the towns of Pinedale and Boulder. B. idahoensis appears to be widespread in the western quarter of the Great Divide Basin as well. The Jack Morrow Hills are known to support several occurrences. There is a single occurrence in the Sweetwater River Basin, just across the divide from the Great Divide Basin, documented in 2003; this signals the need for more sampling in the Sweetwater to determine the actual distribution there. This is the only known occurrence of the species on the east side of the Continental Divide in Wyoming (Beauvais 2004).
Oregon: The range of B. idahoensis in Oregon has not been determined. Recent surveys have found rabbits in Lake, Harney, Malheur, and Deschutes counties. Known areas include Foster Flat, Warner Valley, and north of Sheldon National Wildlife Refuge (NWR) (Carey et al. 2004).
Utah: Occurrences of B. idahoensis in Utah listed in Oliver (2004) have been augmented since the document's printing. Initial survey efforts have focused on the determining of presence or absence, but systematic searches in suitable habitat over large geographic ranges have given us a measure of relative densities. The top three most populous areas include the Western Box Elder County, Northern Rich County, and the Piute/North-western Garfield County. Within these areas, B. idahoensis is considered relatively common. The most notable absence of rabbits occurs throughout the central portion of Utah's Great Basin, which was included in historical estimates of the rabbit's statewide range (Kozlowski 2004).
California: They occur in Mono County California and are abundant from the Bodie Hills to south of Mono Lake. No pygmy rabbits have been relocated to northern California but surveys are on going (Sequin 2004). A recent survey found B. idahoensis present throughout the southern portion of its historic range in California, but did not find active sites in Modoc and Lassen counties in northern California (Larrucea and Brussard 2008).
Nevada: B. idahoensis is found from the state border in the north to the northern end of Nye and Lincoln Counties in the south and from the state border in the east to Vya, Nevada in the west. The pygmy rabbit is still found in most of the higher intermountain regions in the Great Basin Desert of Nevada (Sequin 2004). A recent survey found B. idahoensis present throughout the entire extent of its historic range in Nevada (Larrucea and Brussard 2008).
Montana: They are known from the extreme southwest corner of Montana (Dillon south to Idaho border) (Hays 2004).