Fanning's Illustrated Gazetteer of the United States.... (New York: Phelps, Fanning & Co., 1853), 28.
ARMSTRONG COUNTY, situated in the westerly part of Pennsylvania, and is watered by Alleghany river. Length, 35 miles; mean width, 20, with an area of about 700 square miles. The face of the country is hilly, rocky, and broken, though much of the soil consists of a fertile loam, particularly along the Alleghany river. Courts are held at Kittaning. Pop., in 1820, 10,324; in 1830, 17,695; in 1840, 28,365; in 1850, 29,560.