More than two out of five working households in the Miami-Fort Lauderdale-Pompano, Fla., area paid 50% or more of their incomes in 2009 on housing-related costs. Those households, and literally millions of others around the country, find themselves with this “severe” housing cost burden, and their numbers increased “significantly” in 16 of the country’s 50 largest metro markets.

This morning, the Washington, D.C.-based National Housing Conference's research affiliate, the Center for Housing Policy, released its annual analysis of housing affordability for America’s working households. Its “Housing Landscape 2011” study looked at 2009 and found that more than one in five working households nationwide—10.5 million—classified as having severe housing burdens.

The report defines “working households” as those whose members work at least 20 hours per week, on average, and earn no more than 120 percent of the median income in their area. There were more than 46 million working households in the U.S. in the year tracked, nearly evenly split between owners and renters.

The number of working households spending at least half of their incomes on housing increased by 600,000 in 2009, or 0.6% over 2008, even though the total number of working households declined during that period by 1.1 million.

The portion of owner-occupied working households that spent at least half of their income on housing increased by 1.1 percentage points to 21.2%; for renters, that portion with a severe housing burden grew 2.4 points to 24.5%. The study found that many of these households were trapped in dire financial cycles, as 71% with severe housing burdens earned no more than half of their area’s annual median income.

Housing cost burdens worsened significantly in 25 states in 2009, led by Florida (33% of working households with severe burdens), California (33%), and, surprisingly, New Jersey (29%). Conversely, in four states—Oklahoma, Missouri, Minnesota and Indiana—less than 18% of their working households have severe housing burdens.

Along with Miami, the other markets with the highest percentage of working households with severe burdens were Los Angeles-Long Beach-Santa Ana (37%), Orlando-Kissimmee, Fla. (35%), Riverside-San Bernardino-Ontario, Calif. (35%), and San Diego-Carlsbad-San Marcos, Calif. (34%).

Nine of the 11 metros with the highest rates were in California and Florida. (The other two metros with this dubious distinction were New York City and Las Vegas.)

The study outlines several reasons why housing affordability worsened for low- and moderate-income households in 2009, all of them seemingly related to the current recession. For one thing, these households—and especially renters—worked fewer hours than in 2008. During this period, nominal incomes fell by 5% for working household renters and 4% for owners. Simultaneously, rents crept up. While home prices dropped during this period, the study concludes that they didn’t fall enough to counteract owners’ declining incomes.

“This report’s findings serve as a reminder that falling home values have not solved the affordable housing crisis in America,” said Maureen Friar, president and CEO of the National Housing Conference. “Funding of vital affordable housing programs is still needed even during these tough economic times to ensure stability for America's working families.”

John Caulfield is senior editor for Builder magazine.

Learn more about markets featured in this article: Miami, FL, Los Angeles, CA, Orlando, FL, Riverside, CA, San Diego, CA.