U.S. mortgage rates dropped, with 30-year loans reaching a record low for a fourth straight week, amid signs of improvement in the housing market.

The average rate for a 30-year fixed mortgage fell to 3.56 percent in the week ended today, the lowest in Freddie Mac records dating to 1971, from 3.62 percent. The average 15-year rate dropped to 2.86 percent, also a record, from 2.89 percent, the McLean, Virginia-based mortgage-finance company said in a statement.

Rising home sales and a slowing decline in prices has relieved some strains on the U.S. housing market. The number of homes with loans for more than the properties are worth fell in the first quarter to 11.4 million, or almost 24 percent of all homes with a mortgage, from 12.1 million, or more than 25 percent, in the fourth quarter of last year, according to a report by data provider CoreLogic Inc.

“We do have a little bit of a firmer housing market,” Keith Gumbinger, a vice president of HSH.com, a mortgage-information website based in Pompton Plains, New Jersey, said in a telephone interview. “I don’t think anyone would call it wonderful, but it has improved, or stabilized, over the last few months.”

Contracts to buy previously owned homes rose 5.9 percent last month, matching a two-year high reached in March, the National Association of Realtors reported June 27. Purchases of new U.S. houses rose in May to a two-year high, the Commerce Department said June 25.

Home-loan applications declined in the period ended July 6 for a fourth straight week, according to the Mortgage Bankers Association. A measure of refinancing dropped 3.4 percent from the prior week, while the purchase gauge climbed 3.3 percent, the Washington-based group said.