The nation’s "worst case housing needs" – low-income households who paid more than half their monthly income for rent, lived in severely substandard housing or both – experienced a more than 20 percent increase from 2007 to 2009, according to a report from Department of Housing and Urban Development (HUD). Between 2001 and 2009, the jump was 42 percent.

The increase between 2007 and 2009 is the largest two-year jump since HUD began reporting this segment of the rental market in 1985, according to a statement. Unemployment and under-employment brought 410,000 more households into the worst case needs category for more than one-third of all new cases.

"The report shows a clear link between unemployment and housing needs," said HUD Secretary Shaun Donovan. "A growing economy and new jobs, combined with HUD’s new commitments to produce and preserve affordable rental housing is what we need to reverse this trend."

HUD’s report found that needs cut across all regions of the country and included all racial and ethnic groups, regardless of whether they lived in cities, suburbs or rural areas, according to a statement. Large numbers of worst case needs were also found across various family types including families with children, senior citizens and persons with disabilities.

"The loss of income and the general lack of affordable housing are clearly putting a lot of stress on unassisted families at the lower end of the income spectrum," said Raphael Bostic, HUD assistant secretary for policy development and research.