Breeds western Canada (northern British Columbia east to south-western Saskatchewan) southern in western USA (mainly west of Rocky Mts) to southern California and north-eastern New Mexico. Winters south-western USA (east to western Texas) and Mexico (S, mainly in highlands, to Oaxaca).
 
Population
Estimated population is 3,600,000 (2010).
American Dusky Flycatcher (Empidonax oberholseri) [XC110024]
by Richard E. Webster from Spring Gulch, Chaffee Co., Colorado, United States (call)
American Dusky Flycatcher (Empidonax oberholseri) [XC769231]
by Micah Riegner from Leslie Canyon National Wildlife Refuge, Cochise County, Arizona, United States (call, song phrases)
Subspecies
No subspecies.
Formerly considered conspecific with American Grey Flycatcher (Empidonax wrightii), although appears not to be closely related.