Cities in California, Florida, Nevada and Arizona accounted for the 26 highest foreclosure-filing rates in first-quarter 2009, according to RealtyTrac data tracking metro areas with a population of at least 200,000. However, experts warn that foreclosures going forward may not remain as concentrated. Las Vegas posted the highest metro rate, with 4.48% of its housing units receiving a foreclosure filing during the quarter, which amounts to one in every 22 homes — more than seven times the national average.  Merced, Calif., documented the second highest metro rate, with 4.21% of its housing units receiving a foreclosure filing — one in every 24 homes. Other metro areas in the top 10 were the California cities of Stockton, Riverside-San Bernardino, Modesto, Bakersfield, and Vallejo-Fairfield, along with Phoenix and Port St. Lucie, Fla. “The metro areas with the highest levels of foreclosure activity in the first quarter of 2009 paint a picture of concentrated problems in a relatively small number of hard hit areas,” said James J. Saccacio, chief executive officer of RealtyTrac. Metros such as Burlington-South Beach Burlington, Vt., Lincoln, Neb., and Tuscaloosa, Ala., however, are faring comparatively, all posting foreclosure rates under .02%. Other metros with low foreclosure rates include Utica-Rome, N.Y., Houma-Bayou Cane-Thibodaux, LA, Charleston, WV, Kennewick-Richland-Pasco, Wash., Lafayette, La., Longview, Texas and Asheville, N.C. Saccacio said RealtyTrac expects many of the hardest-hit metro areas to experience high levels of foreclosure activity throughout 2009, but warned other markets would rise up the ranks as unemployment rates surge throughout the U.S. Last week, RealtyTrac reported the number of U.S. properties that received a foreclosure filing jumped 24% in the first quarter from a year earlier, as foreclosure moratoriums were lifted. Wells Fargo & Co. (WFC), JPMorgan Chase & Co. (JPM), Fannie Mae (FNM) and Freddie Mac (FRE) all said they have increased foreclosure activity in recent weeks as a result of timed-out moratoriums. Write to Kelly Curran at kelly.curran@housingwire.com. Disclosure: The author held no relevant investment positions when this story was published. Indirect holdings may exist via mutual fund investments.