A gap in the map
Look at a watershed map of the Northeast and Rome jumps out: the east-flowing Mohawk River and west-flowing Wood Creek come within a few miles of each other on dead-flat ground. Carry your canoe across that gap — one to six miles depending on the season and water levels1 — and you could paddle, with portages around falls, from New York Harbor to Lake Ontario and the interior of the continent.
The Oneida controlled and worked this portage for generations; colonial records call it the Oneida Carrying Place.2 Carrying freight, guiding traders and provisioning travelers made it both a livelihood and a point of leverage.
Forts on the portage
Whoever held the Carrying Place held the door between empires, so the British lined it with forts. The French answered: on March 27, 1756, a French-led force destroyed Fort Bull at the Wood Creek end — one of the war's early shocks in the region.3 In 1758 the British built their answer — the massive earthwork Fort Stanwix, named for General John Stanwix, at the Mohawk River end of the portage.1
The fort's second life came in the Revolution, when its American garrison withstood the 1777 siege that produced the Battle of Oriskany (that story is here). And in 1768 the fort hosted a landmark negotiation: the Treaty of Fort Stanwix, signed that November 5 by representatives of the Six Nations, which drew a boundary line between British colonies and Haudenosaunee lands — a line pressure and settlement would not respect for long.4
The portage becomes a canal
The logic of the Carrying Place never went away — it just changed technology. In October 1797 the Western Inland Lock Navigation Company completed a short canal connecting the Mohawk and Wood Creek,5 and in 1817 the Erie Canal broke ground on the same flat ground that had made the portage easy. Rome exists where it does because this was always the easiest place to cross between watersheds.