NOTE: The number of congested hours per day are not directly comparable across different urban areas because data collection coverage on the freeway system in each urban area can vary dramatically. In this case, the data cover about 65 percent of all freeway lane-miles in Los Angeles, compared to about 22 percent in Chicago where data collection is focused on a smaller, more congested portion of the network. In addition, Chicago tends to have lower free-flow speeds on its monitored freeway network compared to Los Angeles.
SOURCE: Calculated from data used in preparation of Federal Highway Administration, Urban Congestion Report, April 2004–April 2007.
