This species occurs in the west of the United States and in southwestern Canada. Its range extends from southern British Columbia south to west-central California, montane southern California (San Bernardino Mountains, San Jacinto Mountains, Tehachapi Mountains, Mt. Pinos, Mt. Abel), central Nevada and southern Utah, from the Pacific coast east to north-central Wyoming and western Montana, from near sea level to about 3,050 m (10,000 feet) (Stewart 1977, Stebbins 2003). Its distribution is spotty in many areas, particularly at the southern and eastern fringes of the range. Disjunct populations in the mountains of southern California have been proposed as a distinct species, C. umbratica (Rodriguez-Robles et al. 2001).