If your morning commute is growing shorter it may be because there are fewer cars on the road, according to a report from the federal government.

The Federal Highway Administration released data last week showing Americans drove 3.8 billion fewer miles, or 1.6 percent less, in December 2008 compared to the same month a year earlier.

The decline continued a trend of declining driving into a second year.

"The nation's driving decline is another indication of just how important the president's economic recovery plan is," said U.S. Transportation Secretary Ray LaHood.

The information comes from traffic volumes collected at about 4,000 traffic-counting locations nationwide.

The consecutive 14-month trend of declining driving -- between November 2007 and December 2008 -- now tops 115 billion "vehicle-miles traveled," compared to the same period a year earlier. As it has since the trend began, the decline in rural driving in December 2008 outpaced urban driving.

At 4.8 percent fewer vehicle miles compared to December 2007, the new data show the West -- a bloc of 13 states -- experienced the biggest decline. Thanks to an unusually large snowfall, Oregon and Washington led the nation, at 14.7 percent and 11.1 percent fewer vehicle miles respectively, with the largest single-state declines in December 2008.

Despite the overall national decline, 17 states posted slight increases -- the first identified since August. Colorado led the nation in increased single-month travel, with 5.4 percent more vehicle miles than in December 2007.

The northeast, a bloc of nine states, was the only region to show an overall increase, climbing 0.5 percent.