WASHINGTON — Sales of existing homes fell in December, closing out a horrible year for housing in which sales of single-family homes plunged by the largest amount in 25 years. The median home price dropped for the entire year, the first time that has occurred in four decades.

The National Association of Realtors reported that sales of single-family homes and condominiums dropped by 2.2% in December to a seasonally adjusted annual rate of 4.89 million units.

For the year, sales of single-family homes were down by 13%, the biggest drop since a 17.7% plunge in 1982. The median price for a single-family home dropped 1.8% to $217,000.

That was the first annual price decline on records going back to 1968. The Realtors’ chief economist, Lawrence Yun, said it was likely that the country has not experienced a decline in housing prices for an entire year since the Great Depression of the 1930s.

The new figures underscored the severity of the slump in housing, which has been battered for the past two years after enjoying a boom in which sales set records for five consecutive years.

The housing bust has sent shock waves through the entire economy as defaults have risen, resulting in multibillion-dollar loses for big financial firms whose investments in subprime mortgages have gone sour.

There is a concern that the housing and credit troubles could be enough to push the country into a full-blown recession. After global stock markets experienced a sharp sell-off earlier this week, the Federal Reserve announced a bold three-quarter point cut in a key interest rate and held out the promise of more rate cuts to follow.

The Bush administration and congressional leaders are trying to quickly wrap up negotiations on a stimulus package in an effort to boost consumer and business confidence.

For December, sales were down in all regions of the country. Sales fell by 4.6% in the Northeast, 1.7% in the Midwest, 1% in the South and 2.1% in the West.

The inventory of unsold homes dropped by 7.4%, raising hopes that backlogs that had hit record levels were starting to be reduced, a key factor necessary to prompt a rebound in the market.

While Mr. Yun said he expected sales to start to rebound this spring, other analysts said housing is likely to remain in the doldrums throughout most of 2008, reflecting in part the credit crunch, which has caused lenders to tighten their standards, making it harder for prospective buyers to qualify for loans.