Of 102 counties in the Prairie State, Knox County is 23rd in terms of its size (719 square miles). Knox County is in Western Illinois. There is nearly 1,000 acres of lakefront property for sale in Knox County, Illinois, based on recent Land Network data. The combined market value of farms and rural land for sale here is about $7 million. Browse all waterfront property for sale in Knox 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! The most common type of land for sale by combined acreage in Knox County is undeveloped land.