Anguilla, Antigua And Barbuda, Aruba, Bahamas, Barbados, Belize, Bermuda, Canada (B) (P), Cayman Islands, Colombia, Costa Rica, Cuba, Dominica, Dominican Republic, Grenada, Guadeloupe, Guatemala, Haiti, Honduras, Martinique, Mexico, Montserrat, Netherlands Antilles, Nicaragua, Panama, Puerto Rico, St Kitts And Nevis, St Lucia, St Pierre and Miquelon (B) (P), St Vincent and The Grenadines, Trinidad and Tobago, Turks and Caicos Islands, USA (B), Venezuela, Virgin Islands (British) (NB), Virgin Islands (U.S.) (NB).
Vagrant to Algeria, Austria, Belgium, Cape Verde, Denmark, Faroe Islands, Finland, France, Germany, Iceland, Ireland, Jamaica, Japan, Morocco, Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland, United Kingdom.
Central Alaska and central Canada east to Newfoundland, south to central and western USA, as far south as northern California, Colorado and Great Lakes region.
 
Population
Estimated population is 1,500,000 (2010).
Ring-necked Duck (Aythya collaris) [XC139900]
by Ian Cruickshank from University of Wyoming (near Laramie), Albany, Wyoming, United States (call)
Ring-necked Duck (Aythya collaris) [XC384686]
by Paul Marvin from Baie-du-Febvre, Nicolet-Yamaska, Qu\u00e9bec, Canada (call)
Subspecies
Considered by some to form superspecies with New Zealand Scaup (Aythya novaeseelandiae) and Tufted Duck (Aythya fuligula), although probably affinities closer to Canvasback (Aythya valisineria), Common Pochard (Aythya ferina) and Redhead (Aythya americana).