Argentina, Belize, Bolivia, Brazil, Canada (B), Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay (NB), USA (B), Venezuela.
Vagrant to Chile, Dominican Republic, Norway, Trinidad and Tobago.
Western and central North America from Alaska south-east to Minnesota, and south to northern Mexico. Winters mostly in South America, especially in northern Argentina, southern Brazil and Paraguay; also some birds in southern and western USA.
 
Population
Estimated population is 490,000 (2010).
Swainson's Hawk (Buteo) [XC604819]
by Paul Marvin from San Bernardino National Wildlife Refuge, Cochise County, Arizona, United States (call, call in flight display)
Swainson's Hawk (Buteo swainsoni) [XC529031]
by id from Departamento de Soriano - Parque Bartolom\u00e9 Hidalgo, Uruguay (call)