It's not just Democrats and liberals who are the reason for the shift on gay marriage.
Beneath the broad support from liberal-leaning demographic groups, is the fact that some of the biggest shifts in favor of gay marriage since 2004 have been from some more unlikely, conservative-leaning blocs -- blue-collar workers, older voters, and Southerners, according to NBC News/Wall Street Journal polls over the last decade.
And, even though Democrats are markedly more in favor of gay marriage than independents or Republicans, the vast majority of whom remain against it, all three have moved at almost exactly the same rate.
Blue-collar workers’ views on gay marriage have actually shifted more than any other group since 2004. Eight months before George W. Bush was re-elected, just 18 percent said they were in favor of same-sex marriage, and 80 percent were opposed.
Eight years later, a plurality was in favor. In the December 2012 NBC/WSJ poll, 47 percent said so versus 43 percent who remained opposed.
While that 47/43 split shows blue-collar workers are far less supportive of gay marriage than Democrats (69/22), highly educated (66/28), young (65/29), or urban voters (63/31), it does represent a net change of 66 points – more than any other demographic subgroup since 2004.
Older voters, those 65 and older, remain among the most opposed to same-sex marriage (32/54), but that is actually a 43-point shift more in favor than in 2004, when four-in-five older voters were opposed (16/80).
A majority of voters in the culturally conservative South remain opposed to gay marriage (42/50). But that is far less opposition than in 2004 when, similar to older voters, just 20 percent said they favored same-sex marriage, and 71 percent said they were against. That represents a net change of 43 points more in favor.
Among the political parties, Democrats have increased their support by 39 points, Republicans by 37 points, and independents 36 points. In 2004, almost a majority of Democrats were already in favor of same-sex marriage (49/41) and now stand out for their whopping support (69/22).
Independents narrowly favor gay marriage (46/43), moving from two-thirds opposed (30/63). And while nearly two-thirds of Republicans are still opposed (27/63), they were even more solidly opposed (11/84) in 2004.
Young voters, between ages 18-34, represented the second-largest shift since 2004 – 60 points, going from a solid majority opposing -- 56 percent -- to nearly two-thirds in favor. Northeasterners were the third-largest shift – 48 points, going from a majority opposed to three-in-five in favor. Westerners and white-collar workers moved by 47 points, also going from majorities opposed to majorities in favor.
Women also moved more rapidly than men, going from nearly two-thirds opposed to 57 percent in favor. Men went from two-third opposed to a 44 favor, 46 opposed split.
The only groups who have decreased their support over the past decade have been rural voters, those age 50-64, and Hispanics – despite their overwhelming and historic support for President Barack Obama in 2012. Hispanics, who are largely Catholic, tend to be economically liberal, but socially conservative. (Unfortunately, the NBC/WSJ sample on that question in 2004 was a “split sample,” so the groupings of African Americans and Hispanics was too small to be statistically significant. Therefore, this decrease among Hispanics is from 2009.)
There has also been a big difference in support from the parties since Obama took office. Since 2009, Democratic support has gone up 27 points, independents 16, and Republicans just 12.
A major reason for the continued significant shift among Democrats is because of black voters. African Americans increased their support since Obama’s been president by 35 points.
The biggest shifts since 2009 have come from people who live in cities (+40), blue-collar workers (+36), African Americans (+35), age groups 35-49 (+35) and 18-34 (+32), Democrats (+27), people who live in the suburbs (+27), those who live in the Northeast (+25), and women (+25).
In addition to the graphic at the top right, here are some more numbers:
Since 2009:
Urban +40
Blue collar +36
Black +35
35-49 +35
18-34 +32
Democrats +27
Suburban +27
Northeast +25
Women +25
Overall +20
South +20
White +19
West +18
Independents +16
Midwest +15
White collar +14
Men +14
Republicans +12
65 and older +10
Hispanic -4
50-64 -5
Rural -9
Other 2012 groups of note (which subgroups weren’t broken out in 2009 and 2004):
White working class 48/43
Suburban women 55/36
HS or less 40/50
Some coll 50/42
Coll grad 54/35
Post grad 66/28
Other interesting breakdowns from 2004:
17 Bush advertising states 30/64
12 swing states 31/62
Those who said definitely re-elect Bush 8/87
Those who said definitely defeat Bush 55/37