Air freight is the volume of freight, express, and diplomatic bags carried on each flight stage (operation of an aircraft from takeoff to its next landing), measured in metric tons times kilometers traveled.
About a quarter of the world drives on the left, and the countries that do are mostly old Britishcolonies. The following is a list of countries of the world and the side of the road the inhabitants drive on. Most of the people driving on the left side of the road use right-hand-drive vehicles and vice-versa.
Anchorage, Baltimore, Boston, Charleston, Chicago, Duluth, Hampton Roads, Honolulu, Houston, Jacksonville, Los Angeles, New Orleans, New York, Philadelphia, Port Canaveral, Portland (Oregon), Prudhoe Bay, San Francisco, Savannah, Seattle, Tampa, Toledo
The major ports and harbors selected on the basis of overall importance to each country. This is determined by evaluating a number of factors (e.g., dollar value of goods handled, gross tonnage, facilities, and military significance).
Road density is the ratio of the length of the country's total road network to the country's land area. The road network includes all roads in the country: motorways, highways, main or national roads, secondary or regional roads, and other urban and rural roads."
International Road Federation, World Road Statistics and electronic files, except where noted.
Travel services (% of commercial service exports) covers goods and services acquired from an economy by travelers in that economy for their own use during visits of less than one year for business or personal purposes. Travel services include the goods and services consumed by travelers, such as lodging and meals and transport (within the economy visited).
Vehicles per populated land area Units: Vehicles/Populated LandArea (in km2) Units: Air pollution is generally greatest in densely populated areas. To take this into account, we used the Gridded Population of the World dataset available from CIESIN and calculated the total land area in each country inhabited with a population density of greater than 5 persons per sq. km. We then utilized this land area as the denominator for the vehicles data.
World Bank, World Development Indicators 2001, Washington, DC: World Bank, 2001