Free City of Tri-Insula

There are or have been several movements regarding secession from the U.S. state of New York. Only one of them – the state of Vermont – succeeded. The most prominent amongst the unsuccessful ones was for the proposed state of Long Island, consisting of everything on the island outside New York City; a state called Niagara, the western counties of New York state; the northern counties of New York state called Upstate New York; making the city of New York a state; a proposal for a new Peconic County on eastern Long Island; and for the boroughs of Staten Island and Brooklyn to secede from New York City.

Article 4, Section 3 of the Constitution of the United States includes a provision that "no new State shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or Parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress." At the time of Vermont's secession in 1777, the Constitution of the United States did not yet exist. By the time Congress recognized Vermont and admitted it to the Union in 1791, the Constitution was in effect and the legislature of New York had consented. All later secession proposals would require similar consent.

Tensions between what eventually became upstate and downstate New York had existed since Leisler's Rebellion in 1689. That rebellion was more heavily supported in the lower Hudson Valley, near modern New York City, than it was in the Albany area, which remained loyal to the English crown (at the time, the Glorious Revolution was underway in England). Although the rebellion was settled in 1691 when Leisler was executed, tensions between the upper and lower Hudson Valley remained high for another two decades afterward.

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