Amazing coincidence that I hear this story on the Canadian/US American border after posting this.
Ira Glass tells the story of a little-known treaty dispute with far-reaching ramifications for our understanding of executive power. The dispute is between the President and one of his appointees…to the International Boundary Commission with Canada. This little-known commission carried out its function without fanfare or incident for over a hundred years, until a couple of retirees in Washington State built a wall in their backyard and, quite literally, set off an international incident. (23 minutes)
Source: The Prez Vs. The Commish.