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Allegany County New York Genealogy and History

Founded: 1806

Named for: Lenape name for the Allegheny River

County Seat: Belmont

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Allegany County History

This was for centuries the territory of the Seneca people, the westernmost nation of the Five Nations of the Haudenosaunee, a confederacy of Iroquoian languages-speaking peoples. European-American permanent settlement did not take place until after the American Revolutionary War and the forced cession by the Seneca of most of their lands in western New York. New York State sold off the lands cheaply to attract new European-American settlers and agricultural development. Allegany County was created by the state legislature on April 7, 1806 when Genesee County, New York was partitioned to set aside some 1,570 square miles (4,000 km2) to the new county. The first County Seat was established at Angelica, New York where it remained for half a century. It was later moved to Belmont, a village located along the Genesee River. On March 11, 1808, the borders were adjusted so that 230 square miles (600 km2) of Steuben County passed to Allegany County, and 600 miles (1,000 km) of Allegany County passed to Genesee County. This established the current border between Genesee and Steuben counties, and reduced the size of Allegany County to 1,200 square miles (3,100 km2). On June 12, 1812, the legislature authorized the attachment of Cattaraugus County, New York to Allegany County for administration reasons, but for practical reasons this action did not take place at that time. However, on April 13, 1814, the eastern half of Cattaraugus County was so attached and administered from Belmont. This attachment was ended on March 28, 1817. With continued settlement through the mid-nineteenth century, the legislature periodically adjusted county borders as new counties were organized in western New York. On April 1, 1846, Allegany County lost 120 square miles (310 km2) to Wyoming County, reducing the size of Allegany County to 1,140 square miles (3,000 km2), and establishing the current border between Allegany and Wyoming counties. On May 11, 1846, Allegany County lost 50 square miles (100 km2) to Livingston County, reducing the total to 1,090 square miles (2,800 km2), and establishing the western portion of the current border with Livingston County. On March 23, 1857, Allegany County lost another 40 square miles (100 km2) to Livingston County, passing the Ossian, New York area to Livingston County, and establishing the current border between them.

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Genealogy Research in Allegany County, New York

Allegany County Clerk
7 Court Street Rm 18
Belmont, New York 14813
Phone: 585-268-9270

The County Clerk's office has marriage records from 1908- 1935, land records from 1807, divorce and court records.

Allegany County Historical Society
Local History and Genealogy
11 E Greenwood St
PO Box 252
Andover, NY 14806
Phone: 607-478-5390

Adjacent counties