Northwest Illinois features deep valleys and an extremely rugged terrain. This terrain ends at about the Rock River, which cuts through this region.
North Central Illinois features much flatter terrain, and larger cities. Rockford is the biggest at 150,000 (2013).
Further south in this region, the land flattens out, although the Illinois River leaves its mark in a deep cut.
Major cities include Rockford, Belvidere, Rock Island, Freeport, La Salle and Sterling.
Jo Daviess County
Rock Island County