A representative sampling of prices for existing single-family homes around the U.S. plummeted to new lows in January, with 16 of the 20 metropolitan areas tracked by the Standard & Poor's/Case-Shiller index posting record annual declines.

The results announced today by S&P paint a gloomy picture (albeit, with a two-month delay) that last year's housing woes have spilled over into 2008. The index tracks both a 10-city composite and a broader 20-city composite-the former plunged 11.4% in January; the latter sank 10.7%.

Nineteen of the 20 metro areas reported price declines in January, and 10 reported double-digit declines. The lone holdout-Charlotte, N.C.-grew 1.8%. David Blitzer, S&P's index committee chairman, said that each of the 20 metropolitan survey areas has declined every month since September 2007.

The hardest-hit markets were Las Vegas and Miami (-19.3% each), followed by Phoenix (-18.2%). Other than Charlotte, the areas that held up best both come from the Pacific Northwest: Portland (-0.55%) and Seattle (-1.3%).

The Case-Shiller index collects data on single-family home re-sales, capturing re-sold sale prices to form sale pairs. Figures are calculated monthly and published with a two month lag.