Economists have come up with all kinds of theories trying to explain what’s really hampering the sorry state of our job market. Now new research suggests we can scratch at least one culprit off the list – underwater mortgages, which some argue have kept many from taking jobs that require them to relocate. Because these homeowners can’t afford to pay off mortgages worth more than their properties, they find themselves stuck in their homes as home prices nationwide continue to plummet.

Economists Colleen Donovan and Calvin Schnure call this the “lock-in” effect. As the housing crisis set in and home prices spiraled down sharply, many found themselves unable to move, according to a working paper, which analyzed data from the U.S. Census Bureau tracking household mobility. In 2009, mobility fell to 6.8%, compared to 7.8% in 2007. (Read the full paper here.)

But while more households found it financially difficult to move, the trend has not worsened America’s high unemployment rate, the study found.

That’s because in areas where home prices fell steepest, the drop in mobility was largely associated with the decline in local (within the state) moves, which are less likely related to job relocations. Households tend to move out of state for job opportunities. The researchers found that out-of-state moves actually rose in areas where home prices fell sharpest, such as Arizona, Michigan and Florida.

“This suggests that, rather than restricting mobility, severe house price declines may trigger moves out of state, and thus may actually reinforce job mobility related to regional economic shocks,” the study found.

The findings certainly help answer a common debate among economists and policymakers. They’ve been trying to figure out whether America’s unemployment problems have more to do with a mismatch of people with available jobs than simply insufficient consumer demand.

“Our research shows that structural issues appear not to play a role in joblessness but rather a sluggish economy is more likely the problem,” says Donovan, a senior economist at Freddie Mac (FMCC). The working paper, which has not yet been published, is making its rounds through economist circles and blogs. It’s not affiliated with the Virginia-based mortgage company.

Though the findings answer a pressing question, it’s not altogether good news. Many of those who moved out of state for work likely defaulted on their mortgages and lost their homes. So while it’s a positive that underwater mortgages aren’t trapping homeowners from relocating for jobs, there’s still a huge cost to the overall economy. One of the key reasons why large publicly traded U.S. companies, most already flush with cash, haven’t been hiring is because of lack of demand for their products and services. Until executives see consumers willing to spend more, it’s hard for most to justify spending more themselves on headcount or new investments.

So in many ways, underwater mortgages aren’t entirely off the hook.