Residential housing starts fell 18.9 percent from October to November - what some experts are calling the worst month since record-keeping began in 1947 - the Commerce Department reported today.

Single-family starts dropped 16.9 percent to a record low of 441,000 units. Building permits fell 15.6 percent overall, and those for single-family construction, which economists consider the key number in the report, fell 12.3 percent.

"Single-family permits are the most important numbers in this report because they are accurately estimated," said Patrick Newport, housing economist at IHS Global Insight Inc., of Lexington, Mass.

"There are few, if any, builders in this country actually doing any building," said Joel L. Naroff, TD Bank N.A. chief economist. "They seem to have thrown in the towel."

With hundreds of thousands of unsold units nationally - about 19,000 in this area's suburbs - builders have been trying to cut inventory before starting new homes.

Tighter credit, continued economic uncertainty, growing unemployment, and competition with cut-rate foreclosure sales in Florida and the West have complicated the process.

Single-family permits, which declined in three of the nation's four regions - 34.6 percent in the Northeast - also are leading indicators of future housing activity.

The implication from those numbers is that single-family housing starts are likely to post double-digit declines this month and in January, everywhere but in the West, where they are down just 3.7 percent, Newport said.

The small decline in the West is not as good as it looks, considering that single-family permits are down 85 percent since their peak in September 2005. Foreclosure sales now encompass 40 percent of all home sales in that region.

Veteran Main Line builder Chip Vaughan said he had seen slow times in new housing before, but nothing like this. The 1990s downturn in this area affected existing homes more than new, and Vaughan recalls that it lasted no more than 10 months for him.

While he predicts this one will last into 2010, Vaughan plans to hang in, and he told his 13 employees not to worry.

"We're in good shape," he said. "Even if we have to remodel kitchens, we'll be there when the market is back."

Contact real estate writer Alan J. Heavens at 215-854-2472 or aheavens@phillynews.com.