Rock Island County is in Western Illinois. Of the 102 counties in the Prairie State, Rock Island County ranks 62nd in terms of size (451 square miles). The most common type of land for sale by combined acreage in Rock Island County is undeveloped land. Browse all waterfront property for sale in Rock Island County on the Land Network to find the marina, lakefront and other recreational property that meets your needs, from waterside land perfect as a retirement investment to existing residential waterfront land and property for hunting, fishing and other outdoor-recreation pursuits!