South-western Canada (central and eastern British Columbia and south-western Alberta) and western USA in Rocky Mts and Sierra Nevada (Washington to California and east to Wyoming and western Colorado). Winters in west-central and south-central Mexico (south-eastern Sinaloa to east-central Oaxaca).
 
Population
Estimated population is 1,000,000 (2010).
Calliope Hummingbird (Selasphorus calliope) [XC483902]
by Bruce Lagerquist from Bethell Ridge Road, Yakima County, Washington, United States (display dive)
Calliope Hummingbird (Selasphorus calliope) [XC93595]
by Daniel Lane from Baton Rouge, East B. R. Parish, LA, United States (call)
Subspecies
Genus sometimes merged into Mellisuga. Alternatively lumped into Archilochus.
Proposed subspecies lowei (Guerrero) based on a winter specimen, and claimed differences fall within normal variation.