That's the latest, according to the S&P/Case-Shiller U.S. National Home Price Index, which looks at 20 cities across the country.

Las Vegas recorded a 28.6 percent decline in the past year, according to most recent survey. That barely surpasses Miami, whose prices have fallen 28.3 percent in the past year. Phoenix prices have fallen 27.9 percent in the past year.

The U.S. index fell 15.4 percent.

In fourth, prices fell 25.3 percent in Los Angeles and 24.2 percent in San Diego.

The good news for Las Vegas is that the rate of decline has slowed. It dropped 1.6 percent from May to June, a figure that was less than the 2.6 percent drop in Phoenix, 1.8 percent in San Francisco and 1.7 percent in Miami.

In the April to May period, home prices had dropped 2.9 percent in Las Vegas. The rate of decline may be slowing, said David Blitzer, who heads the index committee at Standard & Poor's. Prices had been falling 2.5 percent a month earlier in the year.

"While there is no national turnaround in residential real estate prices, it is possible that we are seeing some regions struggling to come back, which has resulted in some moderation in price declines," Blitzer says.

None of that compares with Denver and Boston, which have seen three months of consecutive increases, he says.

Dennis Smith, president of Home Builders Research of Las Vegas, says he's not surprised the index has slowed. New-home prices can't fall any further, and the poor condition of some of the foreclosure properties is prompting more buyers to ignore them, Smith says.

Foreclosure properties in good condition are getting multiple offers.

"People are willing to pay a little more for a house in turnkey condition," Smith says. "I hear it from brokers that they have gotten to the point they don't even want to show some of the homes in bad shape because no one wants to buy them. How much more are people willing to pay? It can be $20,000 to $25,000 or $50,000, depending on the house."

Smith says he sees prices falling for at least another six months. One reason is there are many homes whose adjustable rate mortgages are set to increase in October and that will force many homeowners to simply walk away, adding to the inventory, he says.

Woodside Homes has been forced into involuntary Chapter 11 reorganization proceedings after creditors say the builder owes them more than $700 million. The company is expected to file for protection by Sept. 16. It is continuing to build homes and operate in the interim.