Even cities that weathered the housing market crash with relatively little damage are suffering now.

Severe price declines have spread to Dallas, Denver, Minneapolis and Cleveland, which had mostly withstood the bust in housing since 2006. The damage has now gone well beyond cities hit hardest by unemployment and foreclosures, such as Phoenix and Las Vegas.

"We didn't enjoy the highs and the lows like other cities," said Kay Weeks, a Realtor with Ebby Halliday in Dallas, where prices fell nearly 1 percent in March and are expected to keep falling. "But when we get bad news nationally, people take notice and cut back on spending and buying homes."

Home prices in big metro areas have sunk to their lowest since 2002, the Standard & Poor's/Case-Shiller 20-city monthly index showed Tuesday. Since the bubble burst in 2006, prices have fallen more than they did during the Great Depression.

The index, which covers metro areas that include about 70 percent of U.S. households, is updated every quarter and provides a three-month average. The March data is the latest available.

Foreclosures have forced prices down so much that some middle-class neighborhoods have turned into lower-income areas within months.

Prices are expected to keep falling until the glut of foreclosures for sale is reduced, companies start hiring in greater force, banks ease lending rules and more people think it makes sense again to buy a house. In some markets, that could take years. (read more)