I read on the Wikipedia page for the Avey Field State/Laurier Airport:
Also known as Avey Field State/Laurier Airport, it is one of six airports that straddle the Canada–US border. The others are Whetstone International Airport, Coutts/Ross International Airport, International Peace Garden Airport, Piney Pinecreek Border Airport, and Coronach/Scobey Border Station Airport.
Why are there 6 airports that straddle the Canada–US border? That sounds too many to be just a coincidence.