An unemployed man looks over job listings on a board at a New York State Department of Labor Employment Services office. (CHRIS HONDROS/GETTY IMAGES)

In 2010, some 46 percent of working Americans who were eligible to vote did so, compared with 35 percent of the unemployed, according to Michael McDonald, a political scientist at George Mason University. There was a similar turnout gap in the 2008 election.

David Leonhardt says it’s because persistent unemployment means that though many people are unemployed, fewer people have had a recent brush with unemployment than was true in previous recessions:

In 1982, the unemployment rate averaged between 9 and 10 percent — and fully 22 percent of the labor force experienced unemployment at some point during the year. In 2009 (the most recent year of data), the unemployment rate also averaged between 9 and 10 percent, but only (or maybe “only”) 16.4 percent of the labor force experienced unemployment at some point during the year ... the share of the labor force that experienced unemployment in 2009 was lower than in the early 1960s, when the unemployment rate was generally below 7 percent.

Matthew Cameron says it’s because the unemployed are concentrated in populous states that are underrepresented in the U.S. Congress:

In 2010, there were 17 states with working age populations that exceeded the per-state average. Among these states, which accounted for 70 percent of the U.S. working age population, the average unemployment rate was 9.9 percent. The other 33 states with below average working age populations, however, had an average unemployment rate of 8.2 percent. The situation is even starker when looking at the extremes. The average unemployment rate among the 10 most populous states was a whopping 10.3 percent in 2010. Among the 10 least populous states, however, average unemployment was only 7 percent.

I’m sure all of these theories are at least partially right. But they’re missing the big one that has the best evidence behind it: The unemployed don’t have very much money. And it’s money that gets the political system interested in your agenda:

Gilens has been collecting the results of nearly 2,000 survey questions reaching back to the 1980s, looking for evidence that when opinions change, so too does policy. And he found it — but only for the rich. “Most policy changes with majority support didn’t become law,” Hacker and Pierson write. The exception was “when they were supported by those at the top. When the opinions of the poor diverged from those of the well-off, the opinions of the poor ceased to have any apparent influence: If 90 percent of poor Americans supported a policy change, it was no more likely to happen than if 10 percent did. By contrast, when more of the well-off supported a change, it was substantially more likely to happen.”

If 15 million college-educated professionals were unemployed right now, the political system would care.