Here are some of Zillow's findings:
Of U.S. homeowners with a mortgage, about one-third are underwater.
That is to say: 15.7 million people owe more than their home is worth.
Collectively, they owe $1.2 trillion above the value of their homes.
Nevada is worst off of the states: Of homeowners with mortgages there, two-thirds are underwater.
In Las Vegas, 71 percent owe more than their homes are worth -- and 1 in 4 owes more than double the home's value. Yet the vast majority remain current on their payments, with a delinquency rate of about 14%.
Nationwide, in fact, 90% of underwater homeowners are making timely mortgage payments.
Delinquencies on underwater mortgages are especially high in the Miami-Fort Lauderdale metro area: Of the 46.4% of homeowners with mortgages who are underwater, more than a quarter are behind on payments.
Where does your neighborhood stand? A couple of online tools can help you assess the stability of your own area. Zillow has a negative-equity tool that lets you check counties, cities and even down to the ZIP Code level to see what percentage of homes are underwater.
And the Local Initiatives Support Corporation has assembled downloadable, searchable spreadsheets that rank ZIP Codes' relative risk of foreclosure within states and within metro areas. The highest-risk ZIP Code has an index score of 100; a score of 50 represents half the foreclosure risk. For instance, within the hard-hit Las Vegas area, the 89108 ZIP is considered the highest risk, followed closely by 89030 and 89031 in North Las Vegas and 89015 in Henderson, Nev. The 89034 ZIP in Mesquite, Nev., has the lowest risk score. (By the way, we'd love to see these spreadsheets turned into online tools; if you know of any coders who have done so, please let us know in the comments.)