With majority support in 44 states, and more in favor than opposed in 4 others, same-sex marriage is a done deal for most Americans. Besides, it's legal nationwide after a Supreme Court ruling in 2015. But Americans in two states are holding out when it comes to moral approval: Missisippi, where more are opposed to same-sex marriage than in favor of it, and in Alabama, the last state where an outright majority oppose it.
Support rose above 50% for the first time in 2011 and has not gone below that mark since then. Support rose to 60% for the first time in 2015 and has not gone below that mark since then. Support continues to rise while opposition continues to fall each year, driven in large part by a significant generational gap.
From 1988 to 2009, support for same-sex marriage increased between 1% to 1.5% per year, but thereafter support began to rise at an accelerated pace.
As of 2016, 83% of Americans aged 18 to 29 support same-sex marriage.
As of 2018, for the first time in Pew's research, more Americans over 65 favor same-sex marriage than oppose it. To find a broad national demographic opposed, you have to filter your way down to categories like "Republican Boomers" or "Weekly Church Attendees."