THE DIVIDING LINE
To understand the definition of the international boundary in the peace treaty of 1783, we have to begin with a document published twenty years earlier: the royal proclamation of October 7, 1763. Only two of the things it did are pertinent here: it defined the geographical limits of the old Province of Quebec, which was then created, and it announced the establishment of a huge Indian reserve in the heart of the continent.
Hitherto Canada had possessed no fixed boundaries, for Britain and France could never agree upon a dividing line between their empires in America;1 but as soon as they were united, by conquest and cession, definition became possible. Thus it fell to the British Crown to draw the first boundary around old Canada. Two stretches of this boundary were to acquire an unforeseen and lasting international importance. That which ran along the forty-fifth parallel of latitude from the St. Lawrence eastward, and then followed the highlands separating the waters flowing into the Atlantic from those flowing into the St. Lawrence, was copied with slight variation by the Quebec Act of 1774, and was recopied by the Treaty of Paris in 1783. This portion of the present international border, then, comes straight from the definition in 1763, and therefore it is interesting to recall the original purpose of this particular line. It sprang from the solid French character of the newly conquered colony. The authorities in London were consciously cutting off unoccupied territory to the south in order to preserve it for English-speaking settlement.2
Less permanent but much more important was another section of the boundary described in the proclamation of 1763. From the point where the forty-fifth parallel intersects the St. Lawrence, it pursued a direct course to the southern end of Lake Nipissing. Of what is now Ontario, only a narrow ribbon of land lying along the Ottawa remained to Canada. Much more than the whole of modern Ontario was severed, for the hinterland of Canada under French rule stretched out to the Mississippi and down the Ohio to join Louisiana. Though the English colonies had certain paper claims to parts of this enormous territory, these were no better than the corresponding French claim, and the French claim was____________________