Lake America was Lake Ontario, which is part of the Great Lakes, which flows from Lake Superior. What flows into Lake Superior? The freaking Saint Louis River. Which comes from Saint Louis Missouri, obviously. So naturally, a landmark of Saint Louis Lake / River would be shown on the shores of Lake America.

https://en.wikipedia.org/wiki/Saint_Louis_River_(Lake_Superior_tributary)

something about the geese no longer being Canadian, maybe?

It's imagining pro-US Canadian militants joining his cause, I think.