In 2001, most Americans opposed same-sex marriage. Now, as the Supreme Court considers whether it will affirm the right to same-sex marriages nationwide, 36 states have it on the books, and attitudes have flipped: 57% of the population opposed marriage equality in 2001, and today 58% support it.
Though it might seem like a surprisingly fast evolution of social opinion, something similar has happened over and over again in the U.S., as a series of infographics from Bloomberg shows.
Take the right of women to vote. In 1910, only four states allowed it; just a decade later, 23 more joined, leading to the passage of the 19th Amendment. Prohibition also spread quickly: In the 14 years before the country temporarily banned booze, 32 states decided to go dry.
Other issues, like interracial marriage, had a slower start, but similar waves of support. Abortion might have followed a similar pattern, but Roe vs. Wade decided the issue before several states had considered it.
Of course, though attitudes may seem to shift relatively quickly, the initial swell of support often takes a little longer to grow. In the case of same-sex marriage, much of the change happened because of something experts call “demographic metabolism”: As older people pass away, they’re being replaced by new generations with a different view on the issue.
“It turns out that the experience of younger people with regard to gay rights is very different from the experience people had 60 or 70 years ago, when gay people were invisible,” says Michael Rosenfeld, an associate sociology professor at Stanford University, who has studied attitudes on same-sex marriage.
“60 years ago, maybe you wouldn’t have known if your neighbor was gay,” he says. “Now you do know, and that helps people put their gay and lesbian neighbors and coworkers into the context of these are just regular people. That makes the idea that they want a simple right like marriage rights sound not only reasonable–but absolutely essential.”
The shift in attitudes towards same-sex marriage, then, has partly been a slow and steady change over the last 30 or 40 years. But once it reached a certain tipping point–around 50% support–there was a quick surge of new acceptance. “The people who are not sort of really ideologically committed to one side or the other see which way the wind is blowing and they move with that,” Rosenfeld says.
The next attitude shift in the works: Legalization of marijuana. As of now, only four states allow recreational use, but 24 allow medicinal pot. The only question is when the movement will hit the tipping point and the rest will follow.