Traffic Jams Cost Americans $121 Billion In 2011

That figure includes the $2.7 billion that paid for the 2.9 billion gallons of fuel (enough to fill the New Orleans Superdome four times) wasted by idling vehicles.

But the vast majority of the lost money is the result of wasted time.

While that is a lot of money, the cost of traffic jams has been on a downward trend for several years. The financial cost of traffic peaked at $131.2 billion in 2007.

The total hours Americans spent stuck in traffic peaked at 5.94 billion in 2006. It dropped to 5.23 billion in 2008 (a result of the recession, when fewer workers were on the road), and climbed back to 5.52 billion in 2011, far below the 2006 level.

And traffic is not getting notably worse: Overall, congestion rose just 1 percent in 2011. No one is sure exactly what factors are driving the trend, but it is unlikely American drivers will set a new record for miles driven anytime soon.

The Transportation Institute study, the 2012 Urban Mobility Report, was compiled using data provided by INRIX, a traffic analytics and information company.