SearchResearch Challenge (8/12/20): Why are some state boundaries so ... odd?

Why is the US/Canada border so complicated and strange?

There's a lot of discussion about the border between the US and Canada. At the moment, the border is technically closed to US citizens because of COVID, and because of that, there's a certain amount of tension as people from the US try to (and sometimes succeed) at sneaking into Canada.

Naturally, that made me curious about the US/Canada border, so I started looking at it, trying to understand how it came to be. And, naturally, one obvious question is "what's the northernmost point of the contiguous United States?" A quick search tells me that it's here, at Angle Inlet, Minnesota.

The border is mostly a long straight line from Vancouver to the middle of Minnesota, and it follows a jagged line when it snakes around islands in the Great Lakes. But then it gets weird in the middle. The borderline takes a sharp left turn due north in the middle of Minnesota, turns left at Angle Inlet, and then meanders back down to to Wheeler's Point and follows the Rainy River, etc etc.

The odd border between Canada and US at Minnesota

That seems pretty weird to me. In general, there are some oddities in states boundaries that demand their backstories. And that's the theme for this week's Challenges: Why are some state boundaries so odd?

1. Why does the US/Canada border take a sudden left turn after passing eastward of Buffalo Point? What's the story there?

2. Similarly, the place where the states of Kentucky, Tennessee, and Missouri meet is also complicated. There's an enclave of Kentucky that's completely surrounded by Missouri and/or Tennessee. How did this little island of Kentucky come to be? (Extra credit: Earthquakes here??)

A small island (enclave) of Kentucky surrounded by Missouri and Tennessee

A small island (enclave) of Kentucky is surrounded by Tennessee and Missouri. Why?

3. The Upper Peninsula of Michigan is another oddity. Any rational drawing of the map would have this part of Michigan be part of Wisconsin. How is it that this peninsula came to be part of Michigan? (Big hint: Toledo turns out to play a part in this story!)