AUSTIN, Texas – The nation's commuters are adapting to increasing traffic congestion by building delays into their schedules, but at a cost of $121 billion in wasted time and fuel, according to an annual study of national driving patterns released Tuesday.

The new report from the Texas A&M Transportation Institute found that Americans wasted an average of $818 each sitting in traffic in 2011. That also meant more carbon dioxide entering the atmosphere.

The worst commute in the country? Washington. Commuters in the nation's capital needed almost three hours for a trip that should take 30 minutes without traffic, according to the report. That compares to the least congested city – Pensacola, Fla. – where commuters needed only nine extra minutes.