This is the smallest hummingbird in the United States. It nests in the Rocky Mountains and Sierras.
Here is a map of the North American Breeding Range:
Map courtesy of Patuxent Wildlife Research Center, United States Department of the Interior, Laurel, MD. From THE NORTH AMERICAN BREEDING BIRD SURVEY RESULTS AND ANALYSIS, Version 96.3 by J. R. Sauer, J.E. Hines, G. Gough, I. Thomas, B.J. Peterjohn.