Comparing a Canadian-history writer with Pierre Berton is not something that should be done lightly; Berton’s ability to make history accessible to the masses is legendary. However, with Arc of the Medicine Line, Tony Rees has proven himself worthy of such a comparison.

In the late 19th century, several nations had a vested interest in officially delineating the border between Canada and the U.S. along the 49th parallel. Britain had already left Canada and wanted to tidy up unfinished business. The U.S. Congress wanted to signal the end of Manifest Destiny. The Canadian government needed to build a railway to keep B.C. happy. And the First Nations who had fled to Canada in the aftermath of skirmishes with the American military wanted protection from retaliation.

The story of how these groups were able to establish a line from Lake of the Woods to the Continental Divide without major confrontation is nothing short of remarkable. Rees, a former city archivist in both Toronto and Calgary, does a wonderful job of recreating the magnitude of this endeavour, and he grippingly describes the hardships suffered at the hands of the chief antagonist: unpredictable weather.

Rees’s lively writing style, as well as his inclusion of witty and prescient excerpts from both personal letters and official reports, make this an engaging read. The men conducting this survey were awed by the bison, the nomadic life of the First Nations, and the supremacy of fur-trading forts, all well-known symbols of the Old West. The irony here is that their work, in facilitating the construction of the railways, paved the way for the Old West’s eventual destruction.

Readers with an understanding of geographical principles will certainly have the advantage here and are perhaps the book’s main audience. But such knowledge is not required to simply enjoy the story of a world in transition.