The graph below shows the most recent USDOT vehicle-travel data covering the last 25 years. Although vehicle-miles of travel (VMT) grew steadily during most of the Twentieth Century, in recent years the growth rate stopped and even declined a little. It is now about 10% below where it would have been had past trends continued.
This week, I finally got around to looking at the latest (2009) Texas Transportation Institute study on traffic congestion. (1)
Two facts struck me as interesting. First, the great congestion surge of the past decade or two is over. In most large metropolitan areas, congestion (measured as hours lost to congestion per traveler) peaked around 2005, and actually declined in 2005-07. For example, in Atlanta, hours lost to congestion peaked at 61, and decreased to 57 by 2007. Congestion increased in only three of the fourteen largest regions (Washington, Detroit and Houston)- and in each of these by only one hour per traveler.