Source: Airport Council International.
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Freight Traffic at the World's Largest Airports, 2008

Freight airports tend to be different from passenger airports, especially in the United States. The Midwest being the economic centroid of the United States, many air freight forwarders have located their hubs in airports such as Memphis (Federal Express) and Louisville (UPS) that generate little passengers traffic. The importance of Pacific Asian airports is linked with the specific role of the region in the global economy, especially over electronics. Since these products tend to have a high value-to-weight ratio, air transport is particularly suitable for their shipping to North American and Western European markets. Two airports play an intermediate role, Anchorage (Pacific Asia - North America traffic) and Dubai (Pacific Asia - Western Europe traffic).