Macomb is a city located in McDonough County, Illinois founded in 1831. It is situated in western Illinois southwest of Galesburg at 40°27'38' North, 90°40'27' West. As of 2000, the city had a population of 18,558. It is the county seat of McDonough County. According to the United States Census Bureau, the city has a total area of 26.5 km². 25.5 km² of it is land and 1.0 km² of it is water. The total area is.90% water; the East Fork La Moine River flows past the northern part of the city. Macomb is the home of Western Illinois University. Macomb apartments for rent comparison page shows most up to date rent information on Macomb apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.