Decatur ( /dəkeɪtər/) is the largest city and the county seat of Macon County in the U.S. state of Illinois. The city, sometimes called "the Soybean Capital of the World", was founded in 1823 and is located along the Sangamon River and Lake Decatur in Central Illinois. In 2000 the city population was 81,500, and 76,122 in 2010. Decatur is the sixth-most populous city in Illinois, outside of the Chicago Metropolitan Area. According to Sperling's Best Places, Decatur's metropolitan area population is 114,749.
Decatur is a classic Midwest USA small city situated with homes and park areas facing Lake Decatur, and with many historic brick buildings downtown. This city is home of private Millikin University and public Richland Community College. Decatur is a college town with treelined streets and vast industrial and agricultural processing production and is located in the Interior Plains of North America.
In the transition from a manufacturing to a service economy, Decatur has experienced decades of population loss and impending sprawl as new development activity grows to the outer Decatur metro area, seemingly blurring the detectable boundaries of contiguous city limits of neighboring communities Mount Zion, Harristown, and Forsyth.