While foreclosures have drawn a lot of attention, there may be yet another threat: the “shadow inventory” of homes where owners are at least one month delinquent on their payments.

In the eight-county Chicago area, 19 percent of mortgages — representing nearly 1 in 5 residential properties with a loan — are delinquent by at least one month, helping create an inventory of almost 204,000 homes at risk of reverting back to lenders, according to data provided to the Chicago Tribune by John Burns Real Estate Consulting in Irvine, Calif. That “shadow inventory,” as experts define distressed homes not yet put up for sale, is the largest in absolute terms for any metropolitan area in the country.

Based on its calculations, the firm believes that 80 percent of those homeowners eventually will lose their property, either through foreclosure or a short sale, in which the lender permits the home to be sold for less than the value of the loan.

If these figures are correct, or even close to correct, the housing crisis will continue for years to come as they properties eventually come up for sale. This will continue to have a strong effect on housing values and new building starts.

This could also have specific effects for the Chicago region. While most of the foreclosure attention seems to be focused on the Southwest and Florida, this data suggests many homeowners are teetering on the edge of keeping their homes.