Four zip codes in Illinois and one in Missouri hold the dubious honor of hosting the largest share of seriously underwater properties in the aftermath of the U.S. housing market collapse a decade ago, according to ATTOM Data Solutions. A seriously underwater home is defined as a property with a combined estimated loan balance at least 25% higher than the property's estimated market value.

"The share of seriously underwater properties has dropped well below 10% in bellwether housing markets such as California, Washington, Texas, Colorado and New York, but the underwater rate remains stubbornly high in markets where price appreciation has not been as strong during the housing recovery of the last six years," said Daren Blomquist, senior vice president at ATTOM.

• Nationally, more than 5.5 million properties were seriously underwater in the second quarter, or 10.1% of all homes with a mortgage.
• More than half of all properties were seriously underwater in 65 zip codes. 65809 in Springfield, Missouri, led the list at 81% followed by four Chicago area locales: 60134 in Geneva, Illinois at 76%, 60124 in Elgin, Illinois at 75.5%, 60175 in Saint Charles, Illinois at 73.6%, and 60554 in Sugar Grove, Illinois at 71.9%.
• The states with the highest share of seriously underwater properties are Louisiana at 21.7%, Illinois at 18.5%, Missouri at 17.8%, Mississippi at 16.8% and Ohio at 16.2%.
• Among metropolitan areas, the worst off are Baton Rouge, Louisiana at 21%, Toledo, Ohio at 20%, Scranton, Pennsylvania at 19.6%, Youngstown, Ohio at 19.3% and New Orleans, Louisiana at 18.9%.

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