Central and eastern Alaska, western and central Canada and western USA. Non-breeding south to south-western and south-central USA and western and central Mexico.
 
Population
Estimated population is 5,200,000 (2010).
Mountain Bluebird (Sialia currucoides) [XC494266]
by Ryan P. O'Donnell from Coconino National Forest (near Payson), Coconino County, Arizona, United States (call)
Mountain Bluebird (Sialia currucoides) [XC15012]
by Jonathon Jongsma from Trujillo Meadows SWA, Conejos Co., Colorado, United States (song)
Subspecies
No subspecies.
Has been suggested that specific name currucoides inapplicable, and that name arctica is required. Occasionally hybridizes with Eastern Bluebird (Sialia sialis).