S&P/Case-Shiller home-price data indicated a clear double-dip for housing, as a tax-credit-induced bump last year was erased and national prices fell back to mid-2002 levels.

The composite 20-city home price index, a broad gauge of U.S. home prices, posted a 0.8% drop in March from a month earlier and fell 1.1% from a year earlier. The broader national index, which is published on a quarterly basis, dropped 4.2% in the first quarter from the fourth and was down 5.1% from a year earlier.

Nineteen of 20 cities in the index posted annual declines in March — just Washington notched an increase. Seattle and Washington post monthly rises. On a seasonally adjusted basis, which aims to take into account the slower winter selling season, six cities — Los Angeles, Miami, Phoenix, San Francisco, Seattle and Washington, D.C. — posted monthly increases. Tampa prices were flat on a seasonally adjusted basis.

Twelve markets — Atlanta, Charlotte, Chicago, Cleveland, Detroit, Las Vegas, Miami, Minneapolis, New York, Phoenix, Portland and Tampa — hit their lowest points since home values started dropping more than four years ago.

“It’s hard to sell when buyers have the leverage and foreclosures continue to create a gap between distressed sale prices and non-distressed sale prices,” said Henry Mo at Credit Suisse Securities. “Homeowners’ unwillingness to sell remains high given the widespread declines in prices.”

See a sortable table of home prices in the 20 cities in the Case-Shiller index.