As more than 250 mayors gathered in Washington for the winter meeting of the United States Conference of Mayors, many agreed that the collapse of the subprime market had left a growing problem of vacant houses, depressed property values, tighter credit, and a need to cut services to close municipal budget gaps.

“It’s an economic tsunami that is hitting our cities,” said Mayor Douglas H. Palmer of Trenton, the president of the conference. “We need federal action not six months from now, but within the next 30 days.”