It is often assumed that the majority of Americans who don't vote are poor and nonwhite. Not so. While it is true that low-income Americans vote at much lower rates, the majority of nonvoters -- in raw numbers -- are white middle class Americans.
Complete turnout data on the 2012 election is not yet available, but consider the numbers from 2008. According the Census Bureau, 11.1 million voting-age U.S. citizens from families earning under $30,000 did not vote. That's a low of poorer Americans sitting out a presidential election, for sure. But even more middle income Americans sat out the election. About 16 million citizens from households making between $40,000 and $100,000 didn't show up at the polls in 2008.
And, interestingly, some 6 million citzens from households earning over $100,000 did not vote in 2008 -- about the same number of citizens that didn't vote from households earning under $20,000.
What does this data mean? A few things.
First, it suggests that alienation from democratic life crosses all income lines, even if it's strongest among low-income Americans. No big surprises there. Second, it suggests that middle class nonvoters are a much larger sleeping giant than many people seem to realize. By far the largest single group of nonvoters in 2008 -- 8.1 million citizens -- were Americans from households making between $50,000 and $75,000 a year.
The third implication is that greater voter mobilization across the board would help progressives, but not by as much as typically imagined. Exit polls from 2008 show that voters making between $50,000 and $75,000 split almost evenly, with McCain narrowly edging out Obama among the single largest group of voters by income. In 2012, Romney won voters making between $50k and $100k by a solid six percentage points.
More broadly in 2012, Romney won all voters making over $50,000 by 8 points, while Obama won voters making under $50,000 by 22 points.
So what would have happened, roughly speaking, if everyone voted in 2012? Well, in 2008, there were 20.3 million citizens from households making under $50,000 who didn't vote and 18.3 million from households making over $50,000 who didn't vote. If the electorate were roughly unchanged in 2012, and everyone voted, Obama would have picked up another 12 million votes from the under $50k group and Romney would have picked up another 7.6 million. Meanwhile, Romney would have picked up another 9.6 million in the over $50k group and Obama would have picked up 8.2 million of these folks.
Net result: Universal voting by all income groups would have produced another 20 million or so votes for Obama and another 17 million votes for Romney. Obama's total votes would have risen to about 85 million and Romney's would have risen to 78 million.
Overall, Obama would have won the election with around 52.5 percent of the vote -- just a bit more than the 51 percent that he actually got. If the 2012 race were tighter, like the 2000 and 2004 races, universal voting could have been the decisive difference in electing Obama.