A long, cold winter has just gotten a bit chillier for anyone hoping for signs of a thaw in the frozen U.S. housing market.

To no one's surprise, quarterly existing single-family-home figures released by the National Association of Realtors show that the national median fell for the sixth consecutive quarter.

This time, prices slipped 5.8 percent to $206,200 in the 12 months ending in December 2007. The drop in median home prices is the biggest ever recorded by the NAR since it began quarterly surveys in 1979, although the NAR attributes a large part of the decline to difficulties in obtaining mortgage financing due to the recent credit crunch.

Sales for existing single-family homes and condos were down a seasonally adjusted 8.5 percent between the third and fourth quarters of last year, and down 20.9 percent from the fourth quarter of 2006.

More than half of the 150 metropolitan areas surveyed -- 77 -- experienced price declines in the fourth quarter, including 16 markets that saw double-digit drops. The nation's biggest loser was Lansing-East Lansing, Mich., which fell 18.8 percent, to $109,600.

Prices also dropped sharply in Sacramento-Arden-Arcade-Roseville, Calif. (down 18.5 percent, to $297,600); Jackson, Miss. (down 16.8 percent, to $120,900) and Riverside-San Bernardino-Ontario, Calif. (down 16.8 percent, to $338,000).

By contrast, 73 markets saw gains, including 11 with double-digit gains.

"The housing market continues to be hindered by affordability and the large number of homes for sale," says Greg McBride, senior financial analyst at Bankrate.com. "Neither of those issues will be cleared up overnight."

Downward pressure
Markets that registered big gains during the housing bubble continued to experience sharp pricing declines. Las Vegas is typical of formerly booming markets gone bust.

Prices in Vegas continued to sink fast during the fourth quarter of 2007. The median price of an existing single-family home sold in the Las Vegas-Paradise area of Nevada fell 12.8 percent, according to NAR figures.

In fact, prices in December alone fell 4.9 percent from the previous month and 15.1 percent from December 2006, according to Patty Kelley, president of the Greater Las Vegas Association of Realtors.

A combination of factors has forced prices down in Las Vegas, Kelley says. Chief among them is the inability of homeowners to make their mortgage payments. This is especially true of homeowners with adjustable-rate mortgages who have seen their rates escalate in recent months.

Such owners quickly become desperate and must sell their homes at bargain prices, which forces down home values in the region. "We continue to see the impact of short sales and bank-owned properties on our housing market," Kelley says.

Short-sale and foreclosure transactions accounted for almost 40 percent of total sales in Las Vegas at the end of the last year and the beginning of 2008, Kelley says. Kelley characterizes these sales as "the most significant contributor to the drop in our median housing price."

Kelley expects short sales and foreclosure sales to keep prices artificially low for the next couple of months. As a result, "sellers can't expect the same kind of appreciation they would have seen in 2004," Kelley says.

However, Kelley sees a silver lining for buyers sitting on the sidelines. "The good news is that there are great deals out there for people to buy," she says.

McBride agrees that the continued slowdown presents an opportunity for many U.S. buyers. "Falling home prices combined with lower mortgage rates are helping to close the affordability gap that exists in many markets, particularly for first-time homebuyers," he says.

Markets on the rise
Meanwhile, some U.S. markets continue to defy the broader downward trend. The Cumberland area of Maryland and West Virginia experienced the greatest rise in fourth-quarter home values, with prices up 19 percent from a year ago, to $116,600. Prices rose 18 percent in Yakima, Wash. ($170,600) and 14.8 percent in Binghamton, N.Y. ($110,000).

Alice Townson has worked for 18 years as a Realtor in the Kanawha Valley, the industrial region that includes Charleston. Charleston traditionally has been an area of slow and steady economic growth, Townson says. That fact has helped isolate the region from the boom-and-bust cycles prevalent in some other parts of the country.

"We haven't had the peaks of the rest of the country," says Townson, who works for Old Colony Realtors, the largest real estate company in West Virginia. "Therefore, we haven't had the valleys."

Charleston also has avoided the real estate speculation that drives prices sky high. Investors tempted to snap up coastal condos in Miami or to buy houses near the Las Vegas Strip are less likely to be lured in by Charleston's more subtle pleasures.