The Erie Triangle is a roughly 300-square-mile (780-square-kilometre) tract of land that was the subject of several competing colonial-era claims.

It was eventually acquired by the U.S. federal government and sold to Pennsylvania so that the state would have access to a freshwater port on Lake Erie.

Following a surveying effort by Andrew Ellicott representing the Pennsylvanians and James Clinton and Simeon DeWitt representing the New Yorkers, the western edge of New York was set at 20 miles (32 km) east of Pennsylvania's Presque Isle, a small peninsula off the coast of Erie, Pennsylvania.

Following some pressure from the new federal government, all four states surrendered their claims to that entity, which then, in 1792, sold the final rights to the 202,187 acres (81,822 ha) of land to Pennsylvania for $151,640.25 (75¢/acre).

[citation needed] The Erie Triangle is often described as a "tab" or "chimney" attached to the Keystone State.