The Contested Northern Border

On June 15, Lyman Cutlar, a farmer who a couple of months earlier had settled on San Juan Island, shot and killed a neighbor’s pig that was rooting in his garden and eating his potatoes. He offered the neighbor, Charles Griffin, $10 in compensation for the loss of the pig. Griffin refused, demanding $100.   While in most other places this would only have been an insignificant local squabble, on San Juan Island it catalyzed a minor international military confrontation and diplomatic incident.

Britain and the US both claimed the island. Cutlar was an American citizen, Griffin an employee of Britain’s Hudson Bay Company and manager of a large sheep farm that the HBC operated on the island.   When British authorities threatened to arrest Cutlar for shooting the pig, the US military commander in the region dispatched a few troops to the island to protect Americans and American interests. The British responded in kind, positioning warships off the coast. Though the confrontation, which has become known as the Pig War, could easily have escalated if either side fired upon the other, neither side engaged. When word reached their respective capitals, each government quickly moved to defuse the situation. But neither backed down. For the next dozen years both countries stationed troops on the island, if only token contingents, before their dispute was finally settled in 1872 through international arbitration that awarded the US San Juan and all the other islands it claimed.

It’s a good story, the absurdity of which is fortunately comic rather than tragic because it didn’t escalate into violence, as it easily might have. But if we’re searching for root causes (no pun intended) of the confrontation we’d be better served by looking, as Paullin did, a bit deeper than a pig and a potato.   The immediate cause of this incident was ambiguous language in the Oregon Treaty of 1846 that both sides used to defend their claims.

San Juan Water Boundary


That treaty settled most of the US’s and Britain’s competing claims to the Oregon Country, extending the boundary along the 49th parallel from the Rockies to “the middle of the channel which separates the continent from Vancouver’s Island.”   Of the many routes through the islands, which one that was the channel specified in the treaty was open to several interpretations, and of course the two countries each interpreted the geography of the waters and the language of the treaty in ways that would give them the most territory.   The ambiguity of the treaty’s spatial description was itself a product of another important cause of the conflict: the sketchy geographic knowledge of the area. When the treaty was written, maps of the islands in the region at that moment lacked some critical details.

The Atlas’s map of this territorial dispute over the San Juan Islands maps the US’s and Britain’s competing claims and the final border, and the accompanying text provides details about the treaty negotiations.  This is just one of nearly two dozen maps of international boundary disputes included in the Atlas, more than half of which are devoted to the US’s northern boundary with British North America and later Canada.

Most of these disputes stemmed from the same root causes: imperfect geographic knowledge and the ambiguity of geographic descriptions. This was particularly the case with the first borders of the United States as they were described in the Treaty of Paris in 1783, the treaty between Britain and the US that ended the American Revolution. Eighteenth-century geographic knowledge of many parts of North America was sketchy enough that the original boundaries of the US can’t easily be represented on an accurate map. In the Atlas, Paullin’s solution to this problem was to use an inaccurate historical map, the 1755 Mitchell Map, to represent those boundaries, the same map that was used by the negotiators of the treaty.

Negotiations For Peace

This hazy knowledge of North American geography and the inaccuracies of the Mitchell Map led to several ambiguous geographic descriptions of the international boundary in the Treaty of Paris of 1783. In a study of geographic representations, geographer Donna J. Peuquet quipped “try verbally describing the shape of Canada or the United States” to underscore the value of maps. For sure, not an easy thing to do, and it’s exactly what that the negotiators attempted in the Treaty of Paris and later the Oregon Treaty. Through the nineteenth and into the twentieth century, the US repeatedly argued with its northern neighbor about how the geographic descriptions in these treaties should be interpreted. Some of the geographic descriptions in these treaties were just vague, ambiguous enough to invite differing interpretations. For instance, the Treaty of Paris referenced “highlands” that would divide New Brunswick from Maine. When, decades later, the two nations sought to clarify that border, they offered very different interpretations of where those highlands were. Britain located them over a hundred miles south of where the US maintained they were—no small difference.




Resolved in the Webster-Ashbury Treaty in 1842, the final border ended up just about halfway between these competing claims.

Sometimes the available surveying technologies were inadequate to accurately demarcate boundaries. The boundary between New York and Quebec as specified in the treaty was clear enough: the 45th parallel from the St. Lawrence River to the Connecticut River.   However unambiguous that language was, a late-eighteenth-century survey of the 45th parallel that was used to establish the border on the ground was off, incorrectly locating the parallel a mile or so north of the true location in some spots.  By the time this was ascertained, the US had begun construction on a fort that was south of that survey line, but a quarter mile mile north of the true 45th parallel—on soil that was, according to the terms of the Treaty of Paris, part of British North America. Neither willing to part with that incomplete facility—which became known as “Fort Blunder”—nor with the rest of the territory that had been treated as American soil, the US successfully negotiated to make the eighteenth-century survey line the border.

The Forty-Fifth Parallel

Sometimes the geographic knowledge of the period was more than imprecise, it was wildly wrong. The Treaty of Paris established the northwestern border of the US as running from the northwestern-most point of the Lake of the Woods (now in northern Minnesota) west to the source of the Mississippi River. The problem was, the source of the Mississippi was not located to the west but instead to the southeast of the lake.

Lake of the Woods

As Britain and the US renegotiated the border in the first decades of the nineteenth century they accommodated the better but still imprecise knowledge of the geography of this part of North America. The international border would run along the 49th parallel from the Rockies until it intersected the longitudinal line that, in turn, interesected the northwestern most point of the lake. From that intersecting point on the 49th parallel the boundary would be “drawn due north or south (as the case may require).”  That point ended up being north of the 49th parallel, producing one of the few US exclaves, the Northwest Angle, the only part of the continental United States north or the 49th parallel.

Today the US and Canada share the longest border between two nations in the world, one that stretches over 5,500 miles. It’s also the longest unfortified border in the world, the largely peaceful nature of which is often celebrated. (We’re currently in the midst of the 200th anniversary of significant armed conflict between the two nations: the War of 1812 during which the US unsuccessfully invaded Canada). Yet collectively Paullin’s maps make it clear that even in the absence of armed conflict that border has nonetheless been a very contested one.  Browsing through the maps in isolation from one another can make it look like a series of fairly localized and often minor disputes over territory. But if we lay all of these individual maps together we can see something that Paullin doesn’t explicitly state in the Atlas.

With the exception of the long border along the 141st meridian that separates most of Alaska from the Yukon Territory, almost every mile of the land border between the US and Canada was contested. Only the water boundaries—the Great Lakes and the St. Lawrence—between the two countries were relatively free of disputes. Otherwise these maps stretch one to another starting from Maine and New Brunswick, west across the continent to Washington and British Columbia, and north into Alaska and British Columbia.  Nearly the entire border is the product of fierce and often prolonged negotiations.

Today there’s only one unresolved territorial dispute between the US and Canada. Both nations claim two tiny, treeless islands, Machias Seal Island and North Rock, about equidistant between the coasts of Maine and New Brunswick. Both counties defend their claims using language (you guessed it) from the Treaty of Paris of 1783. Of no strategic significance, neither government deems these islands import enough to warrant the diplomatic effort needed to resolve the dispute. The uncertainty about sovereignty in the area has led to some arguments between Canadian and American commercial lobstermen who set traps in the surrounding waters. It’s hard to imagine that jostling between these lobstermen will spark any significant conflict between the two nations. That said, it’s also hard to believe that a hundred and fifty years ago US and British troops were on the verge of shooting each other and potentially starting a war over a killed pig.

Leave a Reply

Your email address will not be published. Required fields are marked *