Anguilla, Antigua And Barbuda, Aruba, Bahamas, Barbados, Belize, Bolivia, Brazil, Canada, Colombia, Costa Rica, Dominica, Dominican Republic, French Guiana, Guadeloupe, Haiti, Honduras, Martinique, Montserrat, Netherlands Antilles, Panama, Peru, Puerto Rico, St Kitts And Nevis, St Lucia, St Vincent and The Grenadines, Turks and Caicos Islands, USA (B), Venezuela.
Vagrant to Cuba, Ecuador, French Polynesia, Jamaica, Virgin Islands (U.S.).
Breeds in boreal zone of southern Canada (from central-eastern British Columbia east to south-western Quebec) and northern USA (northern Minnesota east to northern Michigan). Migrates to lowland South America from eastern Colombia and Venezuela south to northern Bolivia and west-central Brazil).
 
Population
Estimated population is 1,200,000 (2010).
Connecticut Warbler (Oporornis agilis) [XC65818]
by Andrew Spencer from Humboldt Golf Course, Saskatchewan, Canada (song)
Connecticut Warbler (Oporornis agilis) [XC833217]
by Paul Driver from Harriet Wetherill Park West Entrance (near Plymouth Meeting), Montgomery County, Pennsylvania, United States (alarm call)
Subspecies
No subspecies.
Genus sometimes subsumed in Geothlypis. This species appears not particularly closely related to current congeners, and it has been suggested that it may merit placement in a monotypic genus. Reported hybrid with Mourning Warbler (Geothlypis philadelphia) generally considered to have been an aberrant individual of Mourning Warbler (Geothlypis philadelphia).