Figure 1,taken from the State Smart Transportation Initiative, shows,on the y-axis, trillions of vehicle-miles traveled in the United States for each year since 1997,as well as 20-year traffic projections made approximately every two years by the U.S. Department of Transportation (USDOT). Each of the rising colored lines represents a forecast made in a different year. The black line represents actual traffic trends on U.S. roads, which, over this period, never rose as quickly as the forecasters had predicted and actually started a modest decline in 2007.
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