English: Political world map shaded according to the number of vehicles in use in each country and spanning the years 2001-2007. Data is from Wolfram Alpha's international transportation data that includes:
-European Commission. "Transport." Statistics.
-International Road Federation. World Road Statistics.
-United States Department of Transportation. "Highway Statistic Series." Federal Highway Administration.
-United States Department of Transportation. "National Transportation Statistics." Research and Innovative Technology Administration.
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