The new data from Case-Shiller released Tuesday showed that local home prices in March 2012 were down 39 percent from their October 2006 peak. That drop likely means even more homeowners are being pushed underwater—that is, they owe more on the mortgage than their homes are worth. New data out from Zillow last week shows, for the first time, where the most people are underwater, as well as how many of them are behind on their mortgage payments.

In Cicero, Zillow reports that 66.3 percent of Cicero homeowners are underwater, and 26.7 percent of those have fallen behind on their payments. Thus, I’ve calculated that 17.7 percent of Cicero homeowners are behind on underwater mortgages.

Stan Humphries, Zillow’s chief economist, has an optimist’s take on the data: If just over a quarter of the people whose homes have lost considerable value are opting not to pay, that means the other three-quarters are paid up. “The vast majority of the folks who [have] negative equity are still paying their mortgages,” Humphries said. “That’s good news.”

Nevertheless, for homeowners in Cicero the picture is harsh. According to the charts in Chicago’s April issue, home values in Cicero have dropped 68.3 percent since 2006; Zillow says that about 29 percent of homeowners there owe twice what their homes are worth. It’s not hard to see why some of them have opted to stop paying.

More than 17 percent of homeowners are both underwater and behind on payments in Posen, Markham, and the part of Aurora that is in the 60505 ZIP Code.

In the city, the highest figure is 14.3 percent, in the 60653 Zip Code, which includes north Kenwood and Oakland. The median for the 263 Chicago-area localities that Zillow charted is 5.4 percent. Keep in mind that this data shows who’s underwater and delinquent right now; that’s on top of the ranks of homeowners who already lost their homes in the past several years.

At the upper end of the scale are five places where less than 1 percent of homeowners are underwater and behind on their payments. They are Golf, the 60614 and 60657 ZIPs in the city (Lincoln Park and south Lake View), Western Springs, and Kenilworth.

That’s not to say that nobody in those places is underwater. In Lincoln Park (60614), more than 28 percent of mortgages are underwater, according to Zillow, but only 5.8 percent of them are behind on their payments. Why? Affluent people in Lincoln Park may have more assets to draw on to cover the mortgage, and, as Humphries notes, “the water is shallower there.” He means that the difference between the home’s value and the mortgage amount is smaller. Just 7 percent of people in Lincoln Park owe twice what the home is worth, compared to Cicero’s 29 percent.

The report, out last week, is the most granular exploration of where and by how much homeowners are hurting. It uses data from both Zillow and TransUnion, the credit-monitoring agency. I’ve focused on the outliers on the chart, but input any ZIP Code at Zillow’s site, and the data that comes up provides a close look at how homeowners are doing there.

What does a high rate of delinquency say about a location? To a bargain-hunting would-be homeowner, it suggests that new foreclosures will be coming on the market down the line at rock-bottom prices. It also says prices will stay low in those locations for a while, even when other areas have begun to head back up. To an investor, Humphries suggests, it flashes a “buy” sign. Many people who lose their homes in foreclosures will want to rent near where they had been living, he says, so investors who are considering getting into the foreclosure-to-rental game may find those areas worth a look.