From the Pew Forum on Religion
Massachusetts became the first state to legalize same-sex marriage following a ruling by the state’s highest court in 2003. To date, courts, legislatures and voters in 19 states – California, Connecticut, Delaware, Hawaii, Illinois, Iowa, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington state – and the District of Columbia have legalized[homosexual] marriage. In addition, three states – Colorado, Nevada and Wisconsin – have civil unions or domestic-partnership provisions for same-sex couples. Meanwhile, 28 states have constitutional amendments banning gay marriage. To see an interactive map of the United States showing the changes in homosexual marriage state by state, click here.