Significantly altered from its original channel, it flows through a primarily rural farming region of reclaimed cropland, south of Lake Michigan.

The river curves westward and ceases to be channelized as it enters Kankakee County in northeastern Illinois.

Large portions of the area were once marshland associated with the meandering Kankakee River, which, for eight or nine months of the year, was flanked on both sides by wetlands.

The Kankakee marsh was an effective barrier to early southerly exploration of both counties, but the area has been progressively drained by ditches constructed during the past 60 years.

Landscape elements include 1) the nearly level plains of a ground moraine, 2) eolian (wind driven deposits) plains, 3) outwash deposits, 4) the central river basin and 5) end moraines forming the north, middle and southern borders.

The southern half of the Kankakee Basin, south of the main river channel, is characterized by the fine-grained sediments that are wind driven, forming a series of broad eolian sand dunes and ridges.

Within the Kankakee Basin (Lake, Jasper, and Pulaski counties), the rock strata are nearly flat, being at the top of the arch.

Some fishing maps and websites about the river may include road directions to the public ramp at the state line, with outdated information.

As of September 7, 2008, the old iron bridge at the Indiana–Illinois state line often clears the water by only approximately 3 feet (0.9 m), making it possible to pass beneath only in small boats, canoes, etc.

A glacial lake resulting from meltwater from the Wisconsin glaciation breached the moraines (located in what is today northern Indiana) holding it in.

The resultant flood created the bed of the Kankakee River and had even greater impact in what is today the state of Illinois.

In order to reach the rest of the county, it was necessary for residents in this area to travel some distance east to Lemon's bridge, before making the journey south.

A lobby grew among the large landholders in Lake County who advocated the complete drainage of the marsh, but due to the American Civil War and the subsequent economic downturn, little action occurred until the 1880s.

Two of the largest landholders agreed to build a network of drainage ditches in their lands to begin draining the eastern edge of the marsh.

[15] The upper river was also highly channelized with levees to allow easier transport of cut timber from the wetlands to saw mills downstream in Illinois.

The channelization aided in the desiccation of the surrounding wetlands and reduced the river to less than half of its original length.

Starting in the 1980s, federal and state efforts have attempted to restore part of the original floodplain of the river through strategic widening of the levees.

The headwaters of the Kankakee River is southwest of downtown South Bend, Indiana, within the city limits.

An area of wetlands and springs to the northwest of the South Bend Ethanol Plant is the start of the Kankakee River.

[17] The Kankakee River also forms the southern boundary of Porter County, delimiting an area of farm land and wetland forest.

The LaSalle Fish and Wildlife Area dominates both sides of the river, as it makes its exit from Indiana and enters Illinois.

Beyond Momence, the river takes on a more traditional image, flowing across the rolling hills of Kankakee County.