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) [XC441350]
by Thomas Magarian from Opal City, Crooked River National Grasslands, Jefferson County, Oregon, United States (call)
Mountain Bluebird (Sialia currucoides) [XC294915]
by from Beartooth Pass area, Carbon County, Montana, United States (call, flight call)
Subspecies
No subspecies.
Has been suggested that specific name currucoides inapplicable, and that name arctica is required. Occasionally hybridizes with Eastern Bluebird (Sialia sialis).