WASHINGTON -- The number of homeowners stung by the rout in the U.S. housing market jumped last month as foreclosure filings grew by more than 50 percent compared with June a year ago, according to data released Thursday.

San Diego County fared even worse as foreclosure filings jumped by 142 percent compared with a year ago. With initial filings, known as notices of default, still high, it appears the county's housing market will be loaded with foreclosures through the year.

Nationwide, 252,363 homes received at least one foreclosure-related notice in June, up 53 percent from the same month last year, but down 3 percent from May, RealtyTrac Inc. said. One in every 501 U.S. households received a foreclosure filing last month.

Foreclosure filings increased from a year earlier in all but 11 states. Nevada, California, Arizona, Florida and Michigan continued to have the highest foreclosure rates.

Riverside County posted one of the worst foreclosure rates in the state with one June filing for every 90 homes. Because the county started its foreclosure crisis before San Diego, its change from a year ago was less, up 82 percent from June 2007. Like San Diego, Riverside's notices of default numbers remained high.

Irvine-based RealtyTrac monitors default notices, auction sale notices and bank repossessions. More than 71,000 properties were repossessed by lenders nationwide in June, the company said.

While foreclosures continue to rise nationwide, efforts in some states to give borrowers more time before losing their homes appear to be working.

In Maryland, where a new law has increased the time to finalize a foreclosure to 150 days from just 15, foreclosure filings dropped by almost 18 percent from last year's levels. In Massachusetts, which last year passed a similar law, filings dropped almost 3 percent.

Still, the combination of weak housing sales, falling home values, tighter mortgage lending criteria and a slowing U.S. economy has left financially strapped homeowners with few options to avoid foreclosure. Many can't find buyers or owe more than their home is worth and can't refinance into an affordable loan.

Economists project 2.5 million homes nationwide will enter the foreclosure process this year, up from about 1.5 million in 2007.

Analysts say the mortgage industry's effort to assist troubled borrowers is being overwhelmed by the magnitude of the foreclosure crisis, and Treasury Secretary Henry Paulson said earlier this week that many foreclosures are "not preventable," citing borrowers who "took out mortgages they can't possibly afford and they will lose their homes."

Lawmakers and government officials have been struggling to come up with a response to soften the blow for the U.S. economy. Congress is working on legislation that would permit the Federal Housing Administration to provide new, cheaper mortgages to distressed homeowners who otherwise would have difficulty refinancing into more secure government-insured loans. Lenders would have to be willing to take a substantial loss by reducing the amount owed on the loan.

The Bush administration announced Tuesday that it would be ready on Monday to implement an FHA expansion that lets borrowers who've fallen behind on their home payments -- because of mortgage rate resets or other economic hardships -- get more affordable loans.

In the RealtyTrac report, metropolitan areas in California and Florida accounted for nine of the top 10 areas with the highest rate of foreclosure for the third-straight month. That list was led by three California cities: Stockton, Merced and Modesto. The Cape Coral-Fort Myers area in Florida was fourth.

In Nevada, one in every 122 households received a foreclosure-related notice last month, more than four times the national rate.

In today's market, about 50 to 60 percent of borrowers nationally who receive foreclosure filings are now likely to lose their homes, said Rick Sharga, RealtyTrac's vice president of marketing, compared with a typical rate of about 40 percent.

"For more and more homeowners who are getting into foreclosure," Sharga said, "there is a much higher likelihood that they are ultimately going to lose the properties to the bank."