Why Canada’s border is so straight

Lines of latitude and longitude

The Convention of 1818 ran the border from the Lake of the Woods along the 49th parallel to the Rocky Mountains, and the Oregon Treaty of 1846 carried the same parallel on to the Strait of Georgia.^[1]

In the northwest the border with Alaska is a meridian, the 141st. A convention of 1906 appointed commissioners to survey and mark it, and they finished the field work in 1913.^[1] Even the parallel was tidied up later: a treaty of 1925 changed the border on the 49th parallel from a slightly curved line between monuments to a series of straight lines.^[1]

Provinces from a grid

In 1870 Canada took over Rupert’s Land and the North-Western Territory, bought from the Hudson’s Bay Company, and carved the small province of Manitoba out of them.^[3] To divide the land among the company, the railway and homesteaders, the Dominion Lands Survey laid a grid of townships over the prairies from 1871.^[2]

When the North-West was cut into provinces in 1905, the lines came from that grid. Prime Minister Wilfrid Laurier argued the territory was far too big to be one province, and that Alberta was ranching country and Saskatchewan farming country; the split was put on the “fourth initial meridian”.^[5] The Alberta Act describes the province as running from the US border north along British Columbia’s eastern boundary, east along the sixtieth parallel, and back south “along the said fourth meridian”.^[4] On the ground that meridian is 110°W, a line 1,225 km long.^[2]

Once Alberta and Saskatchewan reached the 60th parallel, Manitoba, Ontario and Québec asked to be extended north too, and in 1912 they reached their present limits.^[3] So the 60th parallel became the northern edge of British Columbia, Alberta, Saskatchewan and Manitoba.^[2][3]

“thence easterly along the parallel of the sixtieth degree of north latitude to the fourth meridian in the system of Dominion lands surveys”^[4]

Straight, with steps

Not every line is perfectly straight. The southern half of the Saskatchewan–Manitoba border follows a road allowance in the survey grid, and because the grid has “correction lines” every few townships, the border steps sideways in a series of offset segments. North of 56°20′ N it runs straight along the second meridian, about 102°W.^[2]

Drawing the lines was quicker than marking them. The 60th parallel along Saskatchewan was surveyed from 1954 to 1958, and on 15 August 1963 a ceremony at the corner of Saskatchewan, Manitoba and the Northwest Territories marked the finished survey of the parallel from the Alaska Panhandle to Hudson Bay. An aluminium obelisk there holds letters addressed to officials in 2063.^[2]