Bluebirds are found in every state in the U.S.
except Hawaii, and in much of Canada and Mexico. Distribution
of the three species of bluebirds is as follows. One of more of
the three species breeds in most parts of the lower 48, and in
the extreme southeastern corner of Alaska. They also breed in much
of Canada, except Newfoundland.
The Eastern Bluebird (Sialia sialis) nests throughout eastern North America through Canada, as far west as Saskatchewan and the Great Plains states, south to eastern New Mexico. They winter in the southern part of their breeding range, and south as far as Mexico and Nicaragua.
The Mountain Bluebird (Sialia currucoides) nests in the foothills and mountains of western North America, from east-central Alaska, east to southwestern Manitoba and the Dakotas, south to southern California, northern Arizona, and southern New Mexico. It may winter as far south as Mexico, or as far north as British Columbia. It is the most migratorial bluebird.
The Western Bluebird (Sialia mexicana) nests in western North America from southern British Columbia, east to the Rockies, and south to southern California and western Texas to south-central Mexico. It is the least migratorial bluebird. It winters at lower elevations, where it is common in desert area mesquite groves.
Sources:
Bluebirds in My House, Arnette Heidcamp, 1997
Sialia, Spring 1985, Vol.7, No.2, page 50
.Whither away, Bluebird, Whither away? The blast is chill, yet in the upper sky Thou still canst find the color of thy wing, The hue of May. Warbler, why speed, thy southern flight? ah, why, Thou, too, whose song first told us of the Spring? Whither away?
- Edmund C. Stedman, The Flight of Birds (1833-1908)