NOTE: Each bar represents the degree of departure from the underlying long-term trendline. For example, the December seasonal factor for Chicago of approximately -1 means that, in December in Chicago, the number of congested hours per weekday is approximately 1 hour less than the overall trend for the weekday congestion.
SOURCE: Calculated from data used in preparation of Federal Highway Administration, Urban Congestion Report, April 2004-April 2007.
