An index of national housing prices dropped the most in over two decades during the third quarter, fresh evidence that the nation's housing slump is likely far from over. The S&P/Case-Shiller indices, release this morning, registered a 1.7 percent decline nationally during the third quarter of 2007 -- the largest quarterly drop in the 21 year history of the index. “The declines in the national figure are notable for two reasons,� said Robert J. Shiller, chief economist at MacroMarkets LLC and one of the namesakes behind the indices. “First, the 3rd quarter decline, at 1.7%, was the largest quarterly decline in the index's 21-year history. And, second, the year-over-year decline posted its second consecutive record low at -4.5%. Consistent with prior 2007 reports, there is no real positive news in today's data. Most of the metro areas continue to show declining or decelerating returns on both an annual and monthly basis. All 20 metro areas were in decline in September over August. Even the five metro areas that still have positive annual growth rates -- Atlanta, Charlotte, Dallas, Portland and Seattle -- show continued deceleration in returns.� Below is a chart of each metro area's price performance, click for a larger view: Metro area prices, Q3 2007, Case-Shiller While Tampa remains the metro area with the largest annual decline according to the Case-Shiller numbers, at -11.1 percent, Miami surpassed Detroit in September, reporting a decline of 10 percent over the past 12 months. Detroit and San Diego followed with -9.6 percent each. Eight of the 20 major metropolitan areas used in index calculations reported their lowest recorded annual returns – these cities are Atlanta, Chicago, Las Vegas, Miami, Minneapolis, Phoenix, San Diego, Tampa, & Washington D.C. For more information, visit