Well, I can confirm, at least as of patch 1.1, that the Panama Canal does NOT exist.
Interestingly, I think it was intended to, or will soon. In the entire stretch of Central America, there are NO cities marked on the map except Colon and Balboa, Panama. No canal between those two cities, though, but you can see where they started putting it in (the 'harbor' from both cities goes quite far inland).
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