A study conducted by the Pew Research Center in 2006. Virtually all research on this topic shows that those who don’t vote are most likely to come from disadvantaged sectors and that they don’t vote because they know there is nothing in it for them. “Liberal democracy” is by nature an oligarchical state-capitalist class dictatorship and has been since at least the time of the Roman Republic. Liberal democracy may be preferable to outright dictatorships just as the Roman Republic was preferable to the later Caesarian state cults. But only because there is a wider “circulation of elites” (Mosca). The problem is not people who don’t vote. The problem is people who take the state seriously and actually believe in this stuff.
A recent survey of voting patterns conducted by the Pew Research Center for the People and the Press, in collaboration with the Associated Press, finds large differences among Americans who are not registered to vote, vote only rarely, are intermittent voters, or regular voters. Who Votes, Who Doesn’t, and Why (5 pages, PDF) also suggests that whites, college graduates, the wealthy, and frequent churchgoers are more likely to vote than young people, Hispanics, and citizens with less education and lower incomes.