United States of America (2004-2015)
Canary Islands (2005)
South Africa (2006)
Faroe Islands (2016)
French Guiana (2013
) French Polynesia (2013)
New Caledonia (2013)
Saint Barthélemy (2013)
Saint Martin (2013)
Saint Pierre and Miquelon (2013)
Wallis and Futuna (2013)
New Zealand (2013)
England and Wales (2014)
Pitcairn Islands (2015)
Acension Island (2016)
Isle of Man (2016)
British Antarctic Territory (2016)
Falkland Islands (2017)
On May 22, 2015, Ireland became the first nation in the world to legalize same-sex marriage by popular vote. Irish people amended their constitution to bring in marriage equality by a landslide margin of 62.07% to 37.93%.
Legally, same-sex marriage also should be available in the Dutch Caribbean "municipality" of Sint Eustatius but there's no indication one has occurred.
In the remainder of the Dutch Caribbean, same-sex marriage is not allowed in the Dutch "constituent countries" of Aruba, Curaçao and Sint Maarten, though Dutch marriages from elsewhere are partially recognized.
In the France list above, the linked year takes you to proof of a same-sex marriage taking place in nine of the 11 overseas "departments" and "collectivities." In the remaining two, Saint Barthélemy in the Carribean and Wallis and Futuna in the South Pacific, same-sex marriage is legal, but there's no indication one has occurred.
Mexico is a current hotspot of the marriage-equality movement.
American Samoa (and U.S. territories)
In addition to the 50 states, the U.S. has five territories: American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and U.S. Virgin Islands. A federal court on Guam legalized same-sex marriage on June 5, 2015. The Marianas, Puerto Rico and Virgin Islands (and Guam) were covered by the U.S. Supreme Court's nationwide ruling on June 26, 2015. But American Samoa (population 55,165) seems not to have been. This is why.
U.S. Indian tribes
There are 566 of them, and they are not covered by the June 26, 2015, U.S. Supreme Court ruling that legalized same-sex marriage nationwide. At least 20 tribes, listed below, have legalized same-sex marriage to date. A number of othersfollow the marriage law of the state in which they are located, meaning same-sex marriage is legal within the tribe without any additional tribal action.
Coquille Indian Tribe in Oregon (2009)
Mashantucket (Western) Pequot Tribal Nation in Connecticut (2010)
Suquamish Tribe in Washington (2011)
Port Gamble S'Klallam Tribe in Washington (2012)
Little Traverse Bay Bands of Odawa Indians in Michigan (2013)
Confederated Tribes of the Colville Reservation in Washington (2013)
Pokagon Band of Potawatomi Indians in Michigan (2013)
Iipay Nation of Santa Ysabel in California (2013)
Cheyenne and Arapaho Tribes in Oklahoma (2013)
Leech Lake Band of Ojibwe in Minnesota (2013)
Puyallup Tribe of Indians in Washington (2014)
Eastern Shoshone Tribe and Northern Arapaho Tribe in Wyoming (2014)
Tlingit and Haida Indian Tribes in Alaska (2015)
Oneida Tribe in Wisconsin (2015)
Keweenaw Bay Indian Community in Michigan (2015)
Confederated Tribes of Siletz Indians in Oregon (2015)
Confederated Tribes of Grand Ronde in Oregon (2015)
Oglala Sioux Tribe in South Dakota (2016)
Cherokee Nation in Oklahoma (2016)
Osage Nation in Oklahoma (2017)