U.S. housing prices, as we know, continued a nationwide decline in December. In a report released Tuesday, Integrated Asset Services, LLC, a provider of default management  and residential collateral valuations, revealed just how far they fell. December's decline of 1.1 percent was actually less severe than November's 1.7 percent decline, but consistent month-over-month price drops brought the full-year 2008 decline to 13.8 percent. And since the market's peak at the end of 2006 through December, housing prices fell 19.1 percent. "We're seeing house prices returning to pre-bubble levels and there are no signs of leveling off just yet," said Dave McCarthy, president and CEO of Integrated Asset Services. "But location is still everything, and in this turbulent market the ability of the IAS360 House Price Index to gauge movement at the neighborhood level will make it the most vital house price index to watch for signs of a recovery." The IAS360 tracks home sales down to the neighborhood level, and then rolls up local totals in 360 counties, nine census divisions, four regions, and the nation overall. December's IAS360 House Price found the hardest hit counties in 2008 were typically located --not surprisingly -- in states that experienced the largest gains during the housing bubble, California and Florida in particular. California fared the worst with three of the nation's hardest hit counties: San Joaquin County, down 51 percent from its high in 2006, Monterey County, down 49 percent, and Kern County, down 45 percent. At the U.S. Census region level, both the West and the South experienced double-digit declines for the full year 2008. The West, which dropped a significant 18.4 percent in 2008, fell an even more astonishing 24 percent from its peak in 2006, while the South, down 12 percent during 2008, was off nearly 18 percent from its high. The Northeast posted less severe declines of 9.4 percent for 2008 and 11.7 percent from its peak. The Midwest, despite significant declines, was the least impacted region in the U.S., and posted declines of 7.4 percent in 2008 and 10.4 percent from its peak. If you break the figures down even farther, San Francisco, San Diego, and Miami were the hardest hit areas in 2008. Within San Francisco's metropolitan area, Contra Costa County declined at an astonishing rate of 35.5 percent during 2008 and 42.2 percent since its 2006 peak. Although, San Francisco's Marin County and San Francisco County posted much lower declines of 11.3 percent and 13.9 percent  from the 2006 high, while declines accelerated to 15.4 percent and 16.1 percent across 2008. Write to Kelly Curran at kelly.curran@housingwire.com.