Whitesides County, Illinois (Fanning's, 1853)
Gazetteer/Almanac
WHITESIDES COUNTY, situated on the northwest boundary of Illinois, with Mississippi river on the west, and traversed by Rock river. Area, 770 square miles. Seat of justice, Lyndon. Pop. in 1840, 2,514; in 1850, 5,361.
Fanning's Illustrated Gazetterr of the United States... (New York: Phelps, Fanning & Co., 1853), 390.