Perkawinan sejenis di Amerika Serikat

Perkawinan sejenis di Amerika Serikat was initially established on a state-by-state basis, expanding from 1 state in 2004 to 36 states in 2015, when, on June 26, 2015, same-sex marriage was established in all 50 states as a result of the ruling of the Supreme Court of the United States in the landmark civil rights case of Obergefell v. Hodges, in which it was held that the right of same-sex couples to marry on the same terms and conditions as opposite-sex couples, with all the accompanying rights and responsibilities, is guaranteed by both the Due Process Clause and the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution.

Civil rights campaigning in favor of marriage without distinction as to sex or sexual orientation began in the 1970s. In 1972, the now overturned Baker v. Nelson saw the U.S. Supreme Court decline to become involved. The issue became prominent from around 1993, when the Supreme Court of Hawaii ruled in Baehr v. Lewin that the state's abridgment of marriage on the basis of sex was unconstitutional. The ruling led to federal and state actions to explicitly abridge marriage on the basis of sex in order to prevent the marriages of same-sex couples from being recognized, the most prominent of which was DOMA. In 2003, the Massachusetts Supreme Judicial Court ruled in Goodridge v. Department of Public Health that it is unconstitutional for the state to abridge marriage on the basis of sex. From 2004 to 2015, as the tide of public opinion continued to move forward towards support of same-sex marriage, various state court rulings, state legislation, popular referendums, and federal court rulings established same-sex marriage in 36 states. In 2011, national public support for same-sex marriage rose above 50% for the first time. In 2013, the Supreme Court of the United States struck down DOMA, declaring it to be a violation of the Fifth Amendment to the United States Constitution in United States v. Windsor, leading to federal recognition of same-sex marriage, with federal benefits for married couples connected to either the state of residence or the state in which the marriage was solemnized. In 2015, national public support for same-sex marriage rose to 60% for the first time. In 2015, the Supreme Court of the United States ruled in Obergefell v. Hodges that the right of same-sex couples to marry on the same terms and conditions as opposite-sex couples, with all the accompanying rights and responsibilities, is guaranteed by both the Due Process Clause and the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution.

The most prominent supporters of same-sex marriage are human rights and civil rights organizations as well as the medical and scientific communities, while the most prominent opponents are religious groups. The ruling of the Supreme Court in Obergefell occurred following decades of consistently rising national public support for same-sex marriage in the United States, with support continuing to rise thereafter.

A study of nationwide data from across the United States from January 1999 to December 2015 revealed that the establishment of same-sex marriage is associated with a significant reduction in the rate of attempted suicide among children, with the effect being concentrated among children of a minority sexual orientation.

The United States of America is the most populous country in the world to have established same-sex marriage nationwide.