Once you get away from bodies of water you have an even bigger problem: mass shipping becomes a lot harder and more expensive when you can't use ships. (Yep, it's called that for a reason.)

This is a really big part of why most of the population is in "coastal" areas (including the Great Lakes). Were I cynical about the US government, I would suspect they know this full well and it was a major part of their planning.

(and guess what, I am cynical.)