Northern Illinois is a region of Illinois generally located immediately along and north of I-80 and outside of Chicagoland. While largely rural, it does include Rockford, the third largest city in Illinois, as well as DeKalb, home of Northern Illinois University.
Rock River Valley (Cities and Villages along the Rock River including Rockford, Dixon and Rock Falls-Sterling as well as the nearby countryside in Winnebago, Lee, Ogle and Whiteside Counties as well as the eastern portions of Carroll County.)
Northern Illinois is generally considered to be the area of Illinois north of I-80 and outside of Chicagoland. Definitions might slightly differ to include Kankakee and Grundy counties, which may also be considered part of Central Illinois. Culturally, the entire region is similar to many other rust belt rural areas. Residents tend to be politically conservative.