The Green River flows through northwestern Illinois as a tributary of the Rock River, winding approximately through Lee, Whiteside, Bureau, and Henry Counties before joining the Rock River west of Green Rock in the Quad Cities metropolitan area. The river originates in northern Lee County and flows initially southwestward before turning westward in Bureau County, where it roughly parallels the Hennepin Canal. Much of the Green's course has been straightened and channelized, creating a diverse fishery that supports both warmwater gamefish and provides accessible angling opportunities across multiple counties. The river passes through the town of Amboy and the communities of Colona and Green Rock, offering anglers a blend of agricultural landscape fishing with convenient access points throughout its length.