Arc of the Medicine Line

The border between Canada and the United States- the longest undefended border in the world-was laid out in many stages over more than a century, but the biggest part of the job was the long, (mostly) straight line across the prairies. On September 18, 1872, a full five years after confederation, two large teams of army surveyors-one from each country-met at the Red River on the Manitoba-Minnesota...