The number of U.S. households on the verge of losing their homes to foreclosure is still rising, but the annual increase in May was the smallest in nearly three years.

Foreclosure filings rose nearly 18 percent in May compared with the same month last year, RealtyTrac Inc. said Thursday. It was the smallest yearly gain since June 2006, and a 6 percent decline from April. Ohio had one of the highest foreclosure rates, though filings dropped nearly 13 percent from a year ago.

But don't expect a quick end to the foreclosure crisis. Foreclosures are likely to remain elevated this year and into 2010 as layoffs become the main reason that borrowers default on their home loans.

More than 321,000 households received at least one foreclosure-related notice in May, according to the foreclosure listing firm's report. That means one in every 398 U.S. homes received a foreclosure filing last month.

On a state-by-state basis, Nevada had the nation's highest foreclosure rate in May with one every 64 households receiving a filing. California took the No. 2 slot previously occupied by Florida. California's rate was one in every 144 households.

In Florida, one in every 148 households received a foreclosure filing. Rounding out the top 10 were Arizona, Utah, Michigan, Georgia, Colorado, Idaho and Ohio. The Ohio rate was one out of every 446 households.

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