Home prices as measured by the S&P/Case Shiller Home Price Indices dropped to a new post-housing bust low in March, sinking 4.2% in the first quarter of 2011 after a drop of 3.6% in the fourth quarter of 2010.

The U.S. National Index fell to a reading of 125.41, a new recession low and 5.1% below its level of the same quarter last year. The 10-City Composite Index was down 0.6% to 151.66, 2.9% below March, 2010, and the 20-City Composite was down 0.8% to 138.16, a drop of 3.6% from last March.

Nationally, home prices are back to their mid-2002 levels, but several markets in which subprime mortgages and overbuilding were concentrated fell further below the index benchmark of 100 set in January of 2000. The Case-Shiller data include foreclosed and distressed properties sold on the open market, which are heavily discounted and often not comparable to the rest of the market due to location and condition.

Detroit dropped 2% from February to an index of 67.07, Cleveland fell 1.8% to 96.80, Las Vegas lost 1.1% to 97.18 and Atlanta declined 1.9% to 98.36.Phoenix remained on the edge of fall below the benchmark with an index of 100.27, down 0.5% from February and 8.4% from March of last year.

The biggest declines came in Minneapolis, which lost 3.7% from February and 10% year-over-year to an index of 105.57, followed by Chicago, down 2.4% to110.57 and Charlotte, also off 2.4% to 106.96. Chicago is down 7.6% from the same time last year; Charlotte off 6.8%.

The only markets showing gains were Washington D.C., which, amid continued federal government expansion, gained 1.1% to 182.98, 4.3% ahead of the same time last year, and Seattle, which gained 0.1% to 132.97, still 7.5% below last March.

On the West Coast, the California markets were all down, with San Francisco dropping 0.1% to 129.82, 5.1% behind last March; Los Angeles down 0.3% to 167.77, 1.7% below a year earlier; and San Diego declining 0.8% to 153.88, down 4.0% year-over-year. Portland fell 0.7% to 132.67, down 7.6% from March a year earlier.

Dallas lost 0.8% from February to an index of 112.89 but was only down 2.5% year-over-year. Denver, likewise, fell 0.6% from Februrary to 120.55 but was down 3.8% from March a year earlier.

In Florida, Miami dropped 0.8% month-to-month to 137.28, 6.1% below the index level of March, 2010. Tampa dropped 0.7% to 127.08, 6.9% behind a year before.

New York lost 0.9% to 163.50, down 3.4% from March last year; Boston fell 1.7% to 147.36, sown 2.7% year-over-year.

"This month¹s report is marked by the confirmation of a double-dip in home prices across much of the nation," said David Blitzer, chairman of the Index Committee at S&P. "The rebound in prices seen in 2009 and 2010 was largely due to the first-time home buyers tax credit. Excluding the results of that policy, there has been no recovery or even stabilization in home prices during or after the recent recession."

Learn more about markets featured in this article: Los Angeles, CA.