Right, and I'm observing that 'jcranmer went and looked at the statutory definition of "external boundary" and it conclusively does not not include Lake Michigan; I even cited the statute for you. :)
A reminder here that Lake Michigan is entirely bounded by the United States. I think it's as internal as the Great Salt Lake.
The times I’ve seen Lake Michigan claimed as an external entry point it’s because you can come by boat from outside the US to it.
This is of course ridiculous because by that definition lots of US cities sit next to that sort of body of water including any city on the Mississippi.
A reminder here that Lake Michigan is entirely bounded by the United States. I think it's as internal as the Great Salt Lake.