Bahamas, Belize, Canada (P), Cayman Islands, Colombia, Costa Rica, Cuba, Dominican Republic, French Guiana, Guadeloupe (NB), Guatemala, Guyana, Haiti, Honduras, Jamaica (NB), Mexico, Nicaragua, Panama, Puerto Rico, St Pierre and Miquelon (B) (P), Turks and Caicos Islands, USA (B), Venezuela, Virgin Islands (U.S.) (P).
Vagrant to Ecuador, Greenland, Trinidad and Tobago, United Kingdom.
Northern and central North America from western and central Alaska and Canada (northern Yukon, north-western and southern Mackenzie, northern Saskatchewan and Manitoba east to north-central Quebec, central Labrador and Newfoundland) southern in USA to southern California, central Nevada, northern Arizona, northern New Mexico, Texas (irregular), northern Alabama, northern Georgia and North Carolina (casual in north-eastern Louisiana and Mississippi); winters mainly southern USA coasts and West Indies south to northern coast of South America.
 
Population
Estimated population is 20,000,000 (2010).
Tree Swallow (Tachycineta bicolor) [XC725966]
by Paul Driver from Morro Coast Audubon Society Sweet Springs Nature Preserve (near Baywood-Los Osos), San Luis Obispo County, California, United States (song)
Tree Swallow (Tachycineta) [XC259259]
by Peter Boesman from California: near Lake Tahoe, United States (flight call, flight calls)
Subspecies
No subspecies.
This species (and, by extension, Tumbes Swallow (Tachycineta stolzmanni)), along with Mangrove Swallow (Tachycineta albilinea), White-winged Swallow (Tachycineta albiventer), White-rumped Swallow (Tachycineta leucorrhoa) and Chilean Swallow (Tachycineta meyeni), sometimes placed in separate genus Iridoprocne, but DNA studies indicate close relationship of these taxa with clade consisting of Violet-green Swallow (Tachycineta thalassina), Golden Swallow (Tachycineta euchrysea) and Bahama Swallow (Tachycineta cyaneoviridis), and support placement of all in a single genus. Forms a superspecies with Tumbes Swallow (Tachycineta stolzmanni) and White-winged Swallow (Tachycineta albiventer).
There is one record of hybridization with Cliff Swallow (Petrochelidon pyrrhonota).