From the site: “The 2006 average annual temperature for the contiguous U.S. was the warmest on record and nearly identical to the record set in 1998, according to scientists at the NOAA National Climatic Data Center in Asheville, N.C. Seven months in 2006 were much warmer than average, including December, which ended as the fourth warmest December since records began in 1895.”

Read article at NOAA News Online
TPE Link - Greenhouse Effect and Global Warming; Climate Change: Global Warming

National temperatures for the contiguous United States from 1895 to 2006.

The blue line with asterisks indicates yearly values; the red line are filtered values.
(Courtesy of NOAA)