The 26 American cities with the worst foreclosure problems are concentrated in four states: California, Florida, Arizona and Nevada.

RealtyTrac's latest report on foreclosures for the first quarter says the highest rates were in Las Vegas, Merced, Calif. and the Cape Coral-Fort Myers area in Florida.

Next on the list were the California metro areas of Stockton, Riverside, Modesto, Bakersfield and Vallejo-Fairfield.

Phoenix and Port St. Lucie, Fla. rounded out the top 10.

Outside of the four high-foreclosure states, the worst foreclosure rates were in Boise City, Idaho (No. 27) and Greeley, Colo. (No. 29).

Last week, RealtyTrac reported nearly 804,000 homes received at least one foreclosure-related notice from January through March. That was up from about 650,000 in the same period a year earlier.