The state of same-sex marriage, as of Jan. 6, 2015. ( The Washington Post )

On Tuesday, a day after gay couples were allowed to get married in Miami, same-sex marriages began across the state of Florida. This is already big news because Florida is the third most populous state in the country (it topped New York last year when its population surged to 19.9 million people, the U.S. Census Bureau announced late last month).

Florida joins a remarkably long list of states that have seen same-sex marriages become legal over the last 18 months, a progression that began with the Supreme Court’s landmark 2013 decision in U.S. v. Windsor. The court determined that in states where same-sex marriage is legal, gay couples must receive the same benefits as straight couples.

At the time of the Windsor decision, same-sex marriage was legal in 13 states and the District of Columbia. Since then, a rapid succession of federal courts have struck down state bans, resulting in this startling number in this story by The Washington Post’s Robert Barnes:

With the addition of Florida, more than 70 percent of Americans now live in the 36 states and the District of Columbia where same-sex marriages are allowed, according to estimates by the Williams Institute at the UCLA School of Law.

That number, along with the map at the top of the post, shows the staggering shift that has occurred on the issue in a relatively short time period. Meanwhile, a poll last year found that a majority of Americans (59 percent) supported same-sex marriage. (Similar numbers were also reported by the Pew Research Center and Gallup last year).

Of course, when the Supreme Court acted in 2013, it did not conclusively settle the question of whether same-sex marriage must be legal in all states, so attorneys and activists have been pushing to have the court consider this question. As Barnes explains here, justices will meet this week to consider whether to take up the issue, something they passed up last fall. Their decision could determine whether the map above, showing the state of same-sex marriage at the beginning of 2015, looks dramatically different by the end of this year.