Broome County, New York: History
When counties were established in the Province of New York in 1683, the present Broome County was part of the enormous Albany County, including the northern part of New York State as well as all of the present State of Vermont and, in theory, extending westward to the Pacific Ocean. This county was reduced in size on July 3, 1766, by the creation of Cumberland County, and further on March 16, 1770, by the creation of Gloucester County, both containing territory now in Vermont.
On March 12, 1772, what was left of Albany County was split into three parts, one remaining under the name Albany County. One of the other pieces, Tryon County, contained the western portion (and thus, since no western boundary was specified, theoretically still extended west to the Pacific). The eastern boundary of Tryon County was approximately five miles west of the present city of Schenectady, and the county included the western part of the Adirondack Mountains and the area west of the West Branch of the Delaware River. The area then designated as Tryon County now is organized as 37 counties of New York State. The county was named for William Tryon, colonial governor of New York.
In the years prior to 1776, most of the Loyalists in Tryon County fled to Canada. In 1784, following the peace treaty that ended the American Revolutionary War, the name of Tryon County was changed to Montgomery County, for General Richard Montgomery, who had captured several places in Canada and died attempting to capture the city of Quebec, thus replacing the name of the hated British governor.
In 1789, Montgomery County was reduced in size by the splitting off of Ontario County. The actual area split off from Montgomery County was much larger than the present county, also including the present Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston, Monroe, Niagara, Orleans, Steuben, Wyoming, Yates, and part of Schuyler and Wayne Counties.
In 1791, Tioga County split off from Montgomery County, along with Herkimer and Otsego Counties. Tioga County was at this time much larger than the present county and included the present Broome and Chemung Counties and parts of Chenango and Schuyler Counties.
In 1798, Tioga County was reduced in size by the splitting off of Chemung County (which also included part of the present Schuyler County) and by the combination of a portion with a portion of Herkimer County to create Chenango County.
On March 28, 1806, Broome County was formed by splitting several towns off from Tioga County. At the time, this included all of Broome County's current area, as well as the then-named town of Tioga (renamed the town of Owego in 1813) and the town of Berkshire. Small portions of land were lost to Cortland County and Tompkins County in 1815 and 1817, respectively. The towns of Owego and Berkshire were returned to Tioga County on March 21, 1822, establishing the present-day boundaries of Broome County.