Mercer County is a county located in the U.S. state of Illinois. As of the most recent data available, the county has a population of approximately 16,957 people, with a population density of about 30.23 persons per square mile.
The county spans a total land area of 561.00 square miles (1,453.00 square kilometers). The administrative center and county seat is Aledo, which often serves as a hub for local governance and services. The largest city within the county by population is Aledo.
Geographically, Mercer County experiences varied elevations, with its highest point at Sherrard 800 ft and its lowest point at Keithsburg 549 ft. The region operates in the UTC-6.