The Birth Of Western New York: Treaty of Hartford Explained

December 16, 1786. The birth nobody noticed.

There were no celebrations. No proclamations. No public awareness.

The Treaty of Hartford untangled a century of confusion. Yet there was very little newspaper coverage of the event. Maybe because New England had more important news to cover.

Still, the long-term consequences could not be denied. The Commissioners in Hartford quietly altered the future of more than six million acres.

The birthplace of Greater Western New York was not a battlefield, a frontier settlement, or an Indian council fire. Rather, it took place at a cold negotiating table in Hartford, Connecticut.

It’s ironic that the formal birth of Western New York occurred during a raging snowstorm. The temperatures lingered in the single digits when the Commissioners from New York and Massachusetts first arrived in Hartford on November 30, 1786, and for several days after.¹ “Fahrenheit’s Thermometer” hit a low of 9 below on December 6,² leaving the Commissioners icy cold to match their disposition at the onset of negotiations.

But that freeze was a mere prelude to the main event. The violent nor’easter came with damaging gale-force winds that destroyed goods and property, sending even moored ships ashore and unfortunate others into the sea to be lost forever. Worse yet, it brought “a plentiful fall of snow,” the likes of which had not been seen in many years.³

The bitter cold and biting snow did not keep the delegates from meeting. John Lowell, James Sullivan, Theophilus Parsons, and Rufus King, for the Commonwealth of Massachusetts, and James Duane, Robert R. Livingston, Robert Yates, John Haring, Melancton Smith, and Egbert Benson, for the State of New York, talked for more than two weeks.

Why were some of the most accomplished legal minds in America devoting weeks to a dispute that had remained unresolved for more than a century? The answer lay not only in Western New York, but in crises unfolding across the young republic.

Colonial boundary disputes had festered for more than a century. While the British Crown had previously acted as the ultimate referee in such matters, the Revolutionary War and the independence it brought changed everything.

Well, maybe not quite everything.

The Crown may have been removed, but the claims remained. The Treaty of Paris not only revived these old disputes but also emboldened them. The weak Articles of Confederation offered a solution on paper, but not in practical reality.

The disposition of the Genesee Country was addressed by John Adams in 1774. Appointed in the fall of 1773 together with James Bowdoin to “draw a State of the Claim of this Province to the Lands to the Westward of New York,”⁴ Adams’ exhaustive research was submitted, accepted, and unfortunately lost during the scramble following the British seizure of Boston. Adams later wrote that the report was found prior to the 1786 Hartford negotiations, and Rufus King told him, “…that without that Statement, none of them would have understood any Thing of the Subject, and the Claim would have been lost.”⁵

Massachusetts apparently had Adams’ very powerful legal argument in its hands, supporting its claims. Assuming this is the case, and assuming it believed it could win, why would it bother to negotiate with New York?

It turned out Massachusetts had much bigger problems. The Revolutionary War debt had created a financial strain on the new state. Its government sought to relieve that strain by raising taxes. In theory, this would work, but only for those with the cash to pay the new taxes.

The farmers in Western Massachusetts, unfortunately, were asset-rich and cash-poor. They had invested their cash in their farms. As a result, unless the government could wait until they sold their crops, they would have no cash to pay their taxes.

The government remained obstinate. Political unrest ensued.

And it was coming to a climax just as the Massachusetts Commissioners sat at the negotiating table opposite their New York counterparts. That same snowstorm that struck Hartford in early December hit Massachusetts. It was enough to thwart the efforts of the “insurgents” (the name given by government sympathizers) of Shays’ Rebellion. Three of its primary instigators were captured by the Massachusetts militia and imprisoned. Daniel Shays, nominal leader of this protest, escaped with several hundred of his “regulators” (the name given by those supporting the farmers).⁶

No doubt, as the Commissioners shivered in their quarters, they read accounts of these events in the local newspaper. Perhaps they wished they, too, could have benefited from 60 blankets “Mrs. Jeffery (formerly Mrs. Hayley)” generously bestowed upon the three unhappy prisoners imprisoned for their alleged insurgency.⁷

In a letter to John Adams, Commissioner James Sullivan clearly spells out these concerns. The future Massachusetts governor wrote to the future president of the United States, “we make a poor hand indeed of Governing the state as it is now. Insurgents are every day attacking and Stopping our Courts of Justice. some of the ring leaders have been lately taken by Coupe D main.”⁸

Sullivan not only recognized the ongoing rebellion, but also the weak federal government, his state’s financial difficulties, and the burdens associated with administering a frontier far from the home state. Moreover, with the example of Vermont fresh in his mind, he worried about a “Wyoming-style” revolt such as was occurring in Pennsylvania.

Negotiations in Hartford were becoming less a question of ownership and more a question of responsibility.

Sullivan’s concerns pointed toward a larger realization—one that neither Congress nor generations of colonial officials had fully recognized.

Which ultimately reveals the question nobody had been asking.

Earlier attempts to resolve the New York-Massachusetts controversy through Congress and the Articles of Confederation failed despite the best efforts of both New York and Massachusetts. Delays begat more delays. None of the selected arbitrators would accept the position.

This may have been in part because for generations, officials have been asking the wrong question: who owns Western New York?

Framing the question in this manner forced the issue into a zero-sum black-and-white scenario. It meant someone would win and someone would lose.

But what if the two parties could compromise? Could both sides claim victory?

The Commissioners were among the most brilliant legal minds the young nation would have to offer. Many would go on to take higher jurisprudence roles. Some would play an important part in creating the new constitution.

As such, they were likely familiar with the legal principles of preemption, divided property interests, and how English law frequently separated rights. Their genius was not inventing these concepts. It was recognizing that the controversy involved more than land ownership. The dispute involved multiple rights: sovereignty, jurisdiction, ownership, preemption, and economic benefit.

Their brilliance was in recognizing that these rights did not necessarily belong together. Once the interests were unbundled, the solution became visible.

By December 14^th, the weather had mellowed. A warm spell pushed the nor’easter out to sea. The temperature hovered in the mid-40s.

Things were improving equally well in the meeting room. It was apparent that each state sought different objectives. New York desired sovereignty, jurisdiction, governmental authority, and administrative obligations. On the other hand, Massachusetts wanted preemption rights, economic value, and future purchase privileges.

New York agreed to this arrangement because it preserved territorial integrity and avoided future Vermont-style challenges.

Massachusetts accepted this deal because it retained value, shed the burden of responsibility, gained a potentially marketable asset, and avoided governing a remote frontier.

Massachusetts kept the opportunity. New York inherited the responsibility.

As Sullivan admitted in his letter to Adams on the day the treaty was signed, Massachusetts was relieved to avoid governing so distant a frontier. The Commonwealth had surrendered sovereignty, but it had retained something it valued more: the opportunity to turn western land into desperately needed revenue.

On December 16, 1786, Greater Western New York ceased being a disputed idea and became a legal reality.

The agreement signed that day—known now as the Treaty of Hartford and then as the Hartford Treaty of Cession⁹—transformed overlapping claims into a workable framework. It gave birth to Western New York. Before Hartford, there were overlapping claims, uncertainty, and confusion. After Hartford, there were boundaries, rights, and economic value.

And defining the region is a most important line. A line nobody could see.

The Treaty of Hartford established a line that marks the origin of Western New York. The boundary began on Pennsylvania’s northern border and extended northward to Lake Ontario. The exact wording occupied several paragraphs. Its consequences would shape centuries.¹⁰

This “Preemption Line” became the great divider of New York State. It sets the stage for surveys, sales, and yet more disputes. Through this line, Western New York not only acquired a boundary but also a legal framework for its existence. For the first time, the region is defined by law.

Unlike the Treaty of Paris, the Treaty of Hartford really did change everything. Vermont became possible because competing claims remained unresolved long enough for a separate political identity to take root. Western New York followed a different path. Before settlers could organize a successful independence movement, Hartford settled the underlying dispute.

Ironically, given that it resulted from the weaknesses inherent in the Articles of Confederation, the Treaty of Hartford provides an early example of practical federal problem-solving. Its quick success, together with the concurrent Shays’ Rebellion and other interstate disputes, makes it clearer than ever that the United States needs a new constitution.

Closer to home, the Treaty of Hartford had a more dramatic impact. Sure, it didn’t immediately resolve the occupation issues of Western New York. The British still held the forts. The Seneca still lived on the lands. Yet, it created momentum for change. Legally defining America’s first frontier created a marketable asset and new opportunities. Yes, among those opportunities is unrestrained speculation.

The Treaty of Hartford gave Greater Western New York a legal future. It did not give it peace. Massachusetts had gained an asset it desperately wanted to monetize. New York had gained jurisdiction over a country it scarcely controlled. The Seneca remained in possession of the land itself. British officers still watched from Niagara. Yet beyond the newly established Preemption Line, ambitious men now saw something that had not existed before: a frontier whose uncertainty had been transformed into opportunity.

Hartford had not closed the question of Western New York.

It had opened the market.

The first men to rush through that opening would try to turn land hunger into empire. They would call it a lease.

Others would call it a revolt.

¹ Hartford Courant, Monday, December 4, 1786, p. 2.
² Hartford Courant, Monday, December 11, 1786, p. 3.
³ “New London, Dec. 8.,” Hartford Courant, Monday, December 18, 1786, p. 3.
⁴ “Report on Boundaries, 1773–1774,” Papers of John Adams, volume 3, https://www.masshist.org/publications/adams-papers/index.php/view/ADMS-01-03-02-pb-0303, [retrieved June 27, 2026]
⁵ Ibid.
⁶ “From the Worchester Magazine, Dec. 7.,” Hartford Courant, Monday, December 11, 1786, p. 3.
⁷ Ibid.
⁸ “Letter from James Sullivan to John Adams dated December 16^th, 1786,” Papers of John Adams, volume 18, https://www.masshist.org/publications/adams-papers/index.php/view/ADMS-06-18-02-pb-0525, [retrieved June 27, 2026]
⁹ Supreme Court Appellate Division Fourth, Fralick & Spaulding, Syracuse, 1910, p. 154.
¹⁰ Ibid., pp. 22-23.