Indeed, Las Vegas is the worst city in the nation for underwater mortgages:

But Las Vegas is not alone.
At the end of the first quarter, some 18.8% of U.S. homeowners with a mortgage—9.7 million households—were “underwater” on their mortgage, according to a report scheduled for release Tuesday by real-estate information site Zillow .
While that is an improvement from 19.4% at the end of last year and a peak of 31.4% 2012, those figures understate the problem.
In addition to the homeowners who are underwater, roughly 10 million households have 20% or less equity in their homes, which makes it difficult for them to sell their homes without dipping into their savings. Most move-up homeowners typically use their home equity to cover broker fees, closing costs and a down payment for their next home. Without those funds, many homeowners can’t sell.