Winter range.—The principal winter home of the black-throated blue warbler is in the West Indies where it is found north to the Bahamas (Andros, Nassau, and Watling Islands). East to Puerto Rico (Río Piedras) and the Virgin Islands (St. Croix). South to Puerto Rico (Maricas); Hispaniola (Paraíso, Dominican Republic; and Jérémie, Haiti); Jamaica (Spanishtown); and the Swan Islands. West to the Swan Islands; Cozumel Island; Cuba (Habana); and the Bahamas (Andros). It is also casual north to southern Florida (Sanibel Island, Key West, and Sombrero Key); accidental in Guatemala (Cobán); and in northern South America; Venezuela (Ocumare and Rancho Grande); and Colombia (Las Nubes, Santa Marta region, and Pueblo Viejo).
The species as outlined is divided into two subspecies or geographic races. The black-throated blue warbler (D. c. caerulescens) is found in Canada and in the United States south to Pennsylvania; Cairns' warbler (D. c. cairnsi) breeds in the Appalachian Mountains from southwestern Pennsylvania southward.
Migration.—Late dates of departure from the winter home are: Puerto Rico—Consumo, April 3. Haiti—Morne à Cabrits, May 6. Cuba—Habana, May 11. Bahamas—Cay Lobos, May 14.
Early dates of spring arrival are: Florida—Fort Myers, March 4. Georgia—Fitzgerald, April 11. South Carolina—Spartanburg, April 5. North Carolina—Weaverville, April 19. Virginia—Lynchburg, April 21. District of Columbia—Washington, April 19. Pennsylvania—Swarthmore, April 25. New York—New York, April 28. Massachusetts—Amherst, May 2. New Hampshire—East Westmoreland, April 29. Maine—Auburn, May 3. Nova Scotia—Scotch Lake, May 7. Quebec—Quebec, May 7. Louisiana—New Orleans, March 22. Tennessee—Chattanooga, April 14. Kentucky—Lexington, April 24. Illinois—Urbana, April 26. Ohio—Canton, April 22. Michigan—Battle Creek, April 28. Ontario—Reaboro, May 3. Missouri—St. Louis, April 18. Iowa—Sigourney, April 21. Wisconsin—Ripon, April 28. Minnesota—Hibbing, May 8.
Late dates of the departure of transients in spring are: Florida—Daytona Beach, May 21. Georgia—Darien, May 20. South Carolina—Clemson (College), May 15. North Carolina—Raleigh, May 19. Virginia—Charlottesville, May 22. District of Columbia—Washington, May 30. Pennsylvania—Berwyn, June 3. Ohio—Ashtabula, May 29. Indiana—Fort Wayne, June 2. Michigan—Detroit, June 2. Illinois—Lake Forest, June 8. Wisconsin—Racine, June 4. Iowa—National, May 27.
Late dates of fall departure are: North Dakota—Fargo, October 21 (bird banded). Minnesota—Minneapolis, October 3. Wisconsin—Milwaukee, October 16. Iowa—Sigourney, October 20. Illinois—Chicago, October 25. Michigan—Grand Rapids, November 1. Indiana—Indianapolis, October 14. Ontario—Port Dover, October 27. Ohio—Medina, October 30. Kentucky—Eubank, October 22. Tennessee—Athens, October 18. Mississippi—Gulfport, October 12. Quebec—Montreal, October 15. New Brunswick—Saint John, October 11. Maine—Portland, October 17. New Hampshire—Water Village, October 8. Massachusetts—Cambridge, November 7. New York—Fire Island, October 24. Pennsylvania—Harrisburg, October 24. District of Columbia—Washington, October 29. Virginia—Lexington, October 15. North Carolina—Highlands, November 14. South Carolina—Clemson (College), October 17. Georgia—Athens, November 2. Florida—Fernandina, November 15.
Early dates of fall arrival are: Wisconsin—New London, August 23. Michigan—Grand Rapids, August 26. Ohio—Toledo, August 24. Illinois—La Grange, August 24. District of Columbia—Washington, August 21. Virginia—Charlottesville, September 12. North Carolina—Mount Mitchell, September 1. South Carolina—Mount Pleasant, August 30. Georgia—Savannah, August 28. Florida—Coconut Grove, August 29. Cuba—Cienfuegos, September 2. Dominican Republic—El Río, October 5. Puerto Rico—Las Marías, October 12.
Casual records.—On the Farallon Islands, Calif., a specimen was found dead on November 17, 1886; it had been previously observed for three weeks. In New Mexico a specimen was taken at Gallinas Mountain on October 8, 1904, and on October 9, 1938 another was collected in Milk Ranch Canyon near Fort Wingate. In Bermuda a specimen was collected October 2, 1902; and it is considered a rare winter visitor. An individual spending the winter at a feeding stand in the suburbs of Washington, D. C., was observed closely from December 22, 1930, to January 16, 1931.