Fanning's Illustrated Gazetteer of the United States.... (New York: Phelps, Fanning & Co., 1853), 22.
ALLEGANY COUNTY, situated in the southwestern part of New York. Length, 40 miles; mean breadth, 28, with an area of 1,120 square miles. It is traversed by Alleghany river, along the borders of which there are considerable tracts of alluvion. The surface of the residue of this county is diversified by hill and dale, and is generally well adapted for grazing. Courts are held at Angelica. Pop. in 1820, 9,330; in 1830, 26,218; in 1840, 40,975; in 1850, 37,812.