It breeds from southeastern Montana east through the Black Hills region of South Dakota. It winters at lower elevations in its breeding range south through central Colorado. The head, neck, upper breast, sides, upper flanks, wings, and upperparts are slate gray, while the lower breast, belly, and undertail coverts are white. In males the head, chest, and upper flanks are darker, forming a hood. The bill is pink, sometimes with a darker tip.
Legs are pinkish brown with darker feet.
This is the largest subspecies of Dark-eyed Junco. It is also very large-billed. This junco has 2 distinct white wing bars that are formed by the white tips of greater and median secondary coverts. The common western Dark-eyed Junco. The head, neck, and upper breast are blackish, giving the appearance of a dark hood.