“A cast of colourful and significant historical players populate a fascinating narrative . . .” —Edmonton Journal

“Like the careful surveyors he is writing about, Rees moves the reader from point to point in meticulous fashion.” —Canadian Geographic

Winner, Margaret McWilliams Award for popular history

Bestseller, Calgary Herald

The border between Canada and the United States 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 border. They were there to fix, for the first time, the precise location of the 49th Parallel between the swampy shores of the Lake of the Woods and the summit of the continental divide in the Rockies.

Over the next two years, the members of the International Boundary Commission went about the business of surveying, mapping and placing markers across nearly 900 miles of unforgiving territory. In Arc of the Medicine Line, Tony Rees recounts how through the work of its brilliant naturalists, the Commission created the first accurate descriptions of what was still largely terra incognita. In drawing the Medicine Line across the High Plains, the Boundary Commission defined the final shape of a new nation and ended, once and for all, the old American dream of Manifest Destiny.