The sovereign Mohawk Nation of Akwesasne straddles both borders, thus including territory partly within Ontario, Quebec and New York.

Historians believe the Mohawk Iroquois pushed out or destroyed the St. Lawrence Iroquoians by 1600 and used the uninhabited territory as a hunting and trapping ground.

In the late 1750s, some 30 Mohawk families who had converted to Christianity, who had previously lived at Kahnawake, founded Akwesasne further West (upriver) in what would become Ontario.

[4] The construction of the Cornwall Canal between 1834 and 1842 accelerated the community's development into a regional and industrial economic "capital" for a growing hinterland of towns and villages.

[3][5] The united counties comprises six of the original eight Royal Townships of Upper Canada: Lancaster, Charlottenburgh, Cornwall, Osnabruck, Williamsburgh and Matilda.

Now known as the Lost Villages, the communities were permanently flooded in 1958 during the construction of the St. Lawrence Seaway as the massive Moses-Saunders Power Dam at the western end of the city required a reservoir.

During the War of 1812, a generation after thirteen of the British colonies declared independence and became the United States, the region became a battleground between Americans and the people who would become today's Canadians.

These different groups mixed and integrated over time, with family names and histories reflecting a blending of different backgrounds that became typical of Eastern Ontario.

[10][11] Smaller but nevertheless impressive contributions in the region were made by a host of other migrants, from Jewish traders, craftsmen and merchants, to Eastern European refugees and even a significant body of former slaves.

The British Empire was the first major state in world history to abolish slavery, and Ontario was the place where this process first bore fruit.

[14][15] "Canada" had been stripped from France after the Seven Years' War, and this included roughly the areas now covered by the Canadian provinces of Quebec and Ontario.

Cornwall and the surrounding area, originally called "Royal Settlement #2" and then "New Jamestown", was initially a rough place, and was largely left to its own devices by all levels of government.

Adding to this initial history of pragmatic entrepreneurialism, beginning very early with the founding of the city, provincial and federal governments have typically neglected the area, treating it as little more than a transit corridor, an attitude which reached its apogee when the St. Lawrence Seaway was smashed through the region in the late 1950s, allowing the Canadian and American national economies to permanently bypass the region, leaving it once again to become something of an economic backwater.

Upon their departure from military camps in Montreal, Pointe Claire, Saint Anne, and Lachine in the fall of 1784, Loyalists were given a tent, one month's worth of food rations, clothes, and agricultural provisions by regiment commanders.

David Thompson, the Welsh-Canadian explorer who mapped the Far West and was called the greatest land geographer in history, drew many of his traveling companions from Cornwall's rural hinterland, drawing on Scottish and native settlers, and himself lived in Williamstown.

[17] The City of Cornwall and Akwesasne First Nations reserve are within the Stormont, Dundas, Glengarry census division but is independent of the county.