This species occurs mainly in the west of the United States, extending into extreme southwestern Canada. Its range extends from northern and central California (along the Coast Ranges south to San Luis Obispo County and the Sierra Nevada south to Tulare County) north to the Willamette Valley, Oregon, and also includes the Puget Lowland southwest of Tacoma (at least formerly) and scattered locations on the east side of the Cascades in Washington and north-central Oregon, as well as the southern end of Vancouver Island and the nearby Gulf Islands British Columbia, at elevations from sea level to around 2,010 m (6,600 feet) (Nussbaum et al. 1983, Brown et al. 1995, Leonard and Ovaska 1998, St. John 2002, Stebbins 2003). A record from near McGillivray Lake in south-central British Columbia needs confirmation (Stebbins 2003).