Miami-Dade County became the first place in Florida to allow same-sex couples to marry on Monday, half a day before a gay-marriage ban that has been ruled unconstitutional is lifted in the rest of the state.
The means same-sex couples will now be able to marry in 36 states and Washington D.C.
Here's a look at the path same-sex marriage has taken across the country.
Massachusetts became the first state to allow same-sex marriage in 2004 as the result of a state Supreme Court decision.
Connecticut began issuing same-sex marriage licenses in 2008 following a state Supreme Court decision in favor of eight gay couples who were denied marriage licenses.
Iowa's gay marriage ban was overturned in April 2009 by the state Supreme Court after justices ruled it violated the state constitution.
Vermont became the first state to legalize gay marriage through the legislative process when lawmakers overrode the governor's veto of a same-sex marriage bill in April 2009.
In June 2009, New Hampshire Gov. John Lynch signed into law a bill that allowed equal access to marriage for same-sex couples.
Gay marriage became legal in Washington, D.C., in March 2010 after passage of a law by the D.C. Council.
Gay marriage became legal in New York state on July 24, 2011, under the Marriage Equality Act passed by the state Senate and signed by the governor on the same day.
In Washington, the governor signed a bill allowing gay marriage on Feb. 13, 2012. Opponents got enough signatures for a referendum vote, and the law only went into effect on Dec. 6, 2012, after voters approved the measure.
On March 1, 2012, Maryland's governor signed a bill into law legalizing gay marriage, but opponents gathered enough signatures to force the issue onto the ballot. Voters affirmed the law in a November 2012 state referendum, and the law went into effect on Jan. 1, 2013.
Maine has recognized domestic partnerships since 2004. Lawmakers passed a law to legalize same-sex marriage in 2009, but it was repealed by voters. In November 2012, voters reversed themselves, passing a ballot measure that legalizes same-sex marriage.
Rhode Island became the 10th state to allow gay marriage on May 2, 2013, when Gov. Lincoln Chafee signed into law a bill recognizing such unions. Weddings started when the law took effect Aug. 1.
Delaware was the 11th state in the nation to legalize same-sex marriage after the state Senate approved the measure and the state's governor signed it into law on May 6, 2013. It went into effect in July 2013.
Minnesota became the 12th state to legalize gay marriage with the passage of a bill in the state Legislature in May 2013. The law went into effect in August 2013.
California's domestic partnership registry was the first of its kind in the United States created by a legislature without court intervention when it was enacted in 1999. While it kept the domestic partner registry, voters later banned same-sex marriage, first through a state law and then a constitutional amendment. A federal court overturned California's voter-approved gay marriage ban, known as Proposition 8, in 2010, and the Ninth Circuit Court of Appeals agreed it was unconstitutional in 2012. But the Supreme Court ruled on July 26, 2013, that those who had appealed the Ninth Circuit ruling had no standing in the case, meaning same-sex marriages could resume in California.
New Jersey started allowing same-sex marriages on Oct. 21, 2013. A superior court judge ruled that civil unions, which the state allowed for same-sex couples since 2007, don't go far enough because they, in some cases, illegally prevent them from getting federal benefits. Gov. Chris Christie was initially planning to appeal that ruling, but decided to drop the appeal hours after the first same-sex weddings in the state were performed.
Lawmakers in Hawaii passed legislation legalizing gay marriage in the Aloha State on Nov. 12, 2013. Couples began marrying on Dec. 2.
Illinois has become the 16th state in the nation to legalize same-sex marriage. The law took effect on June 14, 2014.
The New Mexico Supreme Court legalized same-sex marriage in that state in December 2013, declaring it is unconstitutional to deny a marriage license to gay and lesbian couples.
Judges have ruled the same-sex marriage bans in Michigan, Oregon, Pennsylvania and Texas unconstitutional, but those rulings remain on hold pending appeals.
A country circuit judge ruled Arkansas' ban unconstitutional in May, but the state Supreme Court suspended that ruling just days later and halted the distribution of marriage licenses.
A Missouri judge overturned the state's ban on same-sex marriages in November and ordered registrars to start issuing licenses to gay and lesbian couples.
Same-sex couples may also soon be able to marry in Kansas following a federal judge's ruling in November that the state's ban on same-sex marriage violates the U.S. Constitution.
Three states that do not allow gay marriage offer civil unions or domestic partnerships to same-sex couples.
In Nevada, domestic partners are granted all the benefits, rights, obligations and/or responsibilities of marriage. These partnerships have been legal since 2009.
A bill allowing domestic partnerships in Oregon was signed into law on May 9, 2007. An injunction delayed its initial implementation until it was lifted on Feb. 1, 2008.
Civil unions became legal in Colorado on May 1, 2013, a few months after the state’s General Assembly passed legislation allowing for civil unions.
Domestic partnerships have been recognized in Wisconsin since August 2009 and a U.S. appeals court has ruled that the state's gay marriage ban is unconstitutional.
Civil unions became legal in Illinois on June 2, 2011, following passage of a bill by the state Legislature the year before. Same-sex marriage is now legal in both Illinois and Hawaii, but both states will keep civil unions as an option in addition to marriage.
Twenty-nine states have constitutional amendments defining marriage as between one man and one woman. However, three of those states allow same-sex civil unions or domestic partnerships.
Visit this page by the National Conference of State Legislatures for more information on gay marriage laws by state.