The U.S. Army Corps of Engineers estimates that more than 95
percent of overseas trade produced or consumed by the United
States moves through our ports.
Who woulda thought that overseas trade would go through ports.
It could go through ports in Canada or Mexico. It may sound counter-intuitive, but I don't think that possibility can just be dismissed without even looking at the data. I could imagine that things like legal stuff can influence the stream of goods, not just geography. For example, CETA was just signed while the larger agreement that would include the US now has no chance. I don't know if there is anything in there that might compel a US based company to move things through Canada (and their subsidiary there), but at least it has to be investigated, I don't think consequences of such agreements are immediately obvious, at least they are not to me.
I also would not have dismissed air freight so easily. I would think that while it sure delivers a lot less mass I would assume the parts carried by air probably are much more valuable than what's on the ships, so in terms of monetary value I would not have been surprised to see a higher share. Just think of UPS and FedEx and their big fleets.
The alternatives are road/rail (via Canada or Mexico) and air. Presumably very little overseas trade is routed through Canada and Mexico, but it's certainly possible.
I personally would have guessed a higher percentage would come through air than 5%.
A really large amount goes through Canada. The port of Vancouver is bigger than Oakland, and the port of Manzanillo Mexico is only slightly smaller. Both ports have rail connections to the US interior. The Mexican ports have lower market share because they are pretty far from Chinese origins, but if you want to amuse yourself you can Google up a lot of crazy conspiracy theories about the connections between Mexican ports and the US city of Kansas City. Many deranged people believe that the Mexicans are usurping our sovereignty via an obscure customs office in Kansas City that is (barely) connected by rail to the port of Lazaro Cardenas.
