Mercer County is located along U.S. Highway 67 and State Highways 17 and 94 in the U.S. state of Illinois. The Mississippi River is located along the western border of Mercer County and is part of the Yellowbanks Territory, named by the Sauk and Fox Indians because of the yellow, sandy soil along the riverbank. Named after Revolutionary War hero General Hugh Mercer, Mercer County was chartered in 1835 as part of the old Northwest Territory and the Military Tract. As of 2010, the population was 16,434 a drop of 523 from 2000. The county seat is Aledo. Mercer County is one of the four counties that make up the Davenport-Moline-Rock Island Metropolitan Statistical Area.
Cities in Mercer County include: Aledo, Alexis, Joy, Keithsburg, Matherville, New Boston, North Henderson, Reynolds, Seaton, Sherrard and Viola