Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range of P. regilla (sensu lato) extends from southern British Columbia in Canada southward through the United States to southern Baja California, Mexico, and east to Montana, Idaho, and Nevada. The species also occurs on the Channel Islands off southern California (Stebbins 2003). Desert populations in southern California probably were introduced, as were some populations in Arizona. An introduced population occurs in the Queen Charlotte Islands, British Columbia (Reimchen 1990), Canada, and on Revillagigedo Island in Alexander Archipelago, Alaska, where it was introduced in 1960 and is breeding (Waters 1992, Hodge 2004). Overall elevational range extends from sea level to around 3,540 meters (Stebbins 2003).
Under the taxonomic arrangement proposed by Recuero et al. (2006), the distributions of the species in the P. regilla complex presumably would be approximately as follows (Recuero et al. did not provide distributional details):
P. regilla: extreme southern Alaska (introduced), British Coumbia, Washington, western Oregon, and northern California.
P. sierra: central California, Nevada, eastern Oregon, Idaho, western Montana, and presumably extreme northwestern Utah (extirpated?).
P. hypochondriaca: southern California, southern Nevada, southwestern Utah (extirpated?), and western Arizona south to southern Baja California.
This frog is well distributed along 90 km of the lower Colorado River and its backwaters from Davis Camp, just below Davis Dam, to Castle Rock in upper Lake Havasu, but the native versus exotic status of these populations is unclear (Rorabaugh et al. 2004). In Arizona, this species has been recorded as an apparent introduction at Middle Spring and a nearby stock tank in the Virgin Mountains, Mohave County, and at two central Arizona plant nurseries (Rorabaugh et al. 2004). It persisted for at least 19 years and successfully bred at one nursery, where it was reportedly introduced on ornamental plants imported from San Diego (Rorabaugh et al. 2004).