Fanning's Illustrated Gazetteer of the United States... (New York: Phelps, Fanning & Co., 1853), 233.
MONTGOMERY COUNTY, situated toward the south part of Illinois. Area, 684 square miles. Face of the country even; soil fertile. Seat of justice, Hillsborough. Pop. in 1830, 2,953; in 1840, 4,490; in 1850, 6,276.