The western part of New York was Indian territory until after the Revolutionary War. At the conclusion of the Revolution, the ownership of western New York land was disputed between New York State and the State of Massachusetts. Massachusetts claimed land from the Atlantic west, all the way to the Pacific including a large portion of New York State. In 1786 it was agreed that the State of Massachusetts would get the money from the sale of the land of western New York after they got clear title from the Seneca Indians. New York State would be allowed to govern the land thereafter. In 1787 Massachusetts sold the whole of western New York to Oliver Phelps and Nathaniel Gorham. The land of the Phelps and Gorham purchase would become the County of Ontario on Jan. 27, 1789. Mr. Phelps and Mr. Gorham started selling parcels of land from an office in Canandaigua but couldn't sell enough to pay Massachusetts what they were owed. They let the western two-thirds of the land revert to Massachusetts. Mr. Phelps and Mr. Gorham land included all of present day Monroe County except for the present Towns of Hamlin, Clarkson and Sweden. That triangular section containing those towns was sold to Mr. Robert Morris, who started selling parcels.
On April 6, 1796, the town of Northfield in the County of Ontario was formed. It contained what is currently seven of the towns of Monroe County. Genesee County was taken off from Ontario County on March 30, 1802 from the land west of the Genesee River. One of the original towns in Genesee County was the Town of Northampton which is now six of the towns in Monroe County. On Feb. 23, 1821, Monroe County was formed from parts of Ontario and Genesee Counties. The County borders have remained the same since then.
Go to GenWeb of Monroe Co. page.