In secretly recorded comments, Mitt Romney told a private fundraiser that the 47% of American who pay no federal income tax "dependent on government" and predicted they will "vote for the president no matter what."*
Let's not talk about what the comments mean for Romney's election chances. Let's talk about everything we know about "The 47%."
Who They Are
In 2011, 47% of Americans paid no federal income taxes. Within that group, two-thirds still pay payroll taxes. The rest are almost all either (a) old and retired folks collecting Social Security or (b) households earning less than $20,000. Overall, four out of five households not owing federal income tax earn less than $30,000, according to the Tax Policy Center.

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Here's another, slightly wonkier, way to think about the 47%. Divide the group into two halves. The first half is made tax-free by credits and exemptions, the vast majority of which go to senior citizens and children of the working poor. The half that you're left with is so poor, they wouldn't owe federal income taxes even if there were zero tax expenditures.
There are some not-so-poor outliers, like the 7,000 millionaires who paid no federal income taxes in 2011. But for the most part, when you hear "The 47%" you should think "old retired folks and poor working families."
Where They Live
From David Graham, here is the graph of the 47% -- a.k.a. "non-payers" -- by state. The ten states with the highest share of "non-payers" are in the states colored red. Most are in southern (and Republican) states. Meanwhile, the 13 states with the smallest share of "non-payers" are in blue. Most are northeastern (and Democratic) states.

How They Vote
The easiest thing to say about this map is that "non-payers" ironically seem more likely to vote Republican and "payers" seem more likely to vote Democratic. But we can't say that for two reasons.
The first reason is that low income earners are much more likely to vote Democratic, even within Republican states. In 2008, Obama lost Georgia by 5 percentage points but he won 70% of voters who earned less than $30,000 -- which is precisely the demo most likely to owe no federal income tax. Obama lost Mississippi by 14 percentage points, but picked up 66% of voters who earned less than $30,000. As a general rule, Republicans win among richer voters -- both in the red states and the blue. [Graph below via Super-Economy]

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The second factor that complicates our efforts to determine how the 47% vote is that this group is divided between older people and poorer working families. Older people vote in higher numbers. But families earning less than $20,000 voted 30% less than the national average, while households earning more than $150,000 were 30% more likely to vote than average. That data and more is in the Wikimedia Commons graph below. [Editor's aside: Voter turnout is also highly correlated with variables like race, but I don't have data on the 47% broken down by those demographics.]


Why the 47% Meme Matters
Mitt Romney's off-the-record comments were inelegant. But they were also part of a long trend of Republicans attacking the 47% as lazy, or playing by a different set of rules, or not fully contributing to the country. Michele Bachmann went after the non-payers. So did Rick Santorum. And Sen. John Cornyn.
The 47% aren't lucky ducks cheating the system. They're mostly poor working families getting pilloried by the political party that wrote the rules they're following. If the 47% are the monster here, then Republicans helped play the role of Dr. Frankenstein. "Non-payers" have grown in the last 30 years because of marginal tax rate cuts and credits like the EITC passed under Republican presidents and continued by both parties in Congress.
It would be one thing to ask poor working families to pay higher taxes if Republicans were trying to raise money to improve government services. Quite the opposite, Romney's tax plan would, if passed, either reduce revenue or come out neutral by raising taxes on upper-middle class families. Meanwhile, his budget would gruesomely gut Medicaid and income-support programs below their projected 2020 levels.
I don't care about Romney's secret admissions. An 18-month campaign offers a downright luxurious amount of time to say dumb things. But I do care about Romney's public statements and his public stances. In February, Romney told a reporter he was "not concerned about the very poor" because they have a safety net. In August, he backed a budget that slashes the projected growth of that safety net. If only neglecting the plight of low-income families were the sort of thing Romney tried to keep a secret.
*Here's the full quote: "There are 47 percent of the people who will vote for the president no matter what. All right, there are 47 percent who are with him, who are dependent upon government, who believe that they are victims, who believe the government has a responsibility to care for them, who believe that they are entitled to health care, to food, to housing, to you-name-it. That that's an entitlement. And the government should give it to them. And they will vote for this president no matter what...These are people who pay no income tax."