While fewer Americans are falling behind on their mortgage payments, the huge backlog of already delinquent mortgages is finally making its way through the banking system to foreclosure.

Total foreclosure activity rose in the first half of this year from the previous six months, according to online foreclosure sale site RealtyTrac, driven by a jump in new foreclosure actions by lenders.

“Those foreclosure starts are welcome news for prospective buyers and real estate brokers in many local markets where a shortage of aggressively priced inventory has been holding up sales activity. Markets with increasing foreclosure starts will likely see more distressed inventory for sale in the form of short sales and bank-owned properties in the second half of the year,” said Brandon Moore, CEO of RealtyTrac.

More than half of the 212 metropolitan areas RealtyTrac surveys saw increases in foreclosure starts, and of the top ten foreclosure rates in the nation, five of them were in California. Stockton still holds the dubious distinction of the nation’s highest metro foreclosure rate, at more than three times the national average. Despite their high ranking, however, all of the California metros in the top ten actually saw decreasing foreclosure activity overall. In fact, Atlanta was the only metro area with a top ten foreclosure rate to see increasing foreclosure activity in the first half of this year.

While many of the previously hard-hit markets are seeing declines in foreclosures, other cities are seeing big gains. Foreclosure activity increased more than 20 percent from second half of 2011 in Tampa (47 percent), Philadelphia (30 percent), Chicago (28 percent), New York (26 percent), and Baltimore (21 percent).

Foreclosure activity dropped the most in Seattle, WA. Other cities where activity dropped more than 10 percent from the second half of 2011 were San Francisco, Detroit, Los Angeles and Boston.

New foreclosures, known as “starts,” rose in more than 60 percent of metro markets. RealtyTrac ranked the best markets for investing, by looking at where sales prices are increasing but foreclosure discounts are still at 15 percent or higher. Durham, NC, Boston, MA, Cleveland, OH and Phoenix, AZ all made the top ten.