bitflipper
Trivia: if the originally-proposed boundary had been adopted back in the day, both Vancouvers would have been in Washington State. If the British counter-proposal had been accepted, Seattle would today be part of British Columbia. The compromise gave Canada all of Vancouver Island even though its southern end is below the 49th parallel.

 
There were a lot of "interesting" land deals going on between countries in the 1800s that could have changed the face of how the US looks today. I was wondering if the established borders actually have physical surveyed markers somewhere when I found this:
 
"...as it zigzags from the first to the last of the 912 boundary monuments erected by the original surveyors, it deviates from the 49th parallel by up to several hundred feet ...on average, the markers are three arcseconds (i.e. 295 feet) north or south of the 49th parallel."
 
GPS measurements today would probably find a lot of discrepancies in most of the worlds borders.
 

Oddly, Canada did not get one little peninsula that crosses the border, resulting in a U.S. town that you cannot drive to without first going into Canada.

That one seems almost ludicrous as they probably have to rely on Canada for just about everything: "Residents of Point Roberts are Washingtonians, but have to pass through two international border crossings (or travel by water or air) to reach the rest of their state."
 

Pot is legal in this town, but there is no way to legally transport it there (the water route is forbidden by the feds).

 
I'm sure someone's figured out a way.