The river itself whole: the Kankakee, source to mouth

items 1 and 2 — course, length, names, and the confluence

The Kankakee rises one township east of this one and leaves the state as another river's making: its source stands in Portage Township, St. Joseph County, some five miles southwest of South Bend; its modern course runs 133 miles west and southwest across northern Indiana and into Illinois, to the confluence where it joins the Des Plaines to form the Illinois River. The town never sat on it — the river runs along the south of Olive Township, the township's edge, not its seat — and the course that made this township was not a bend of the river but the marsh behind it, drained in the work the farms leg of this run carries whole: a natural river of roughly 240 meandering miles straightened to 133 in the channelisation of 1918–1922. Its names, in sequence at the records' strength: the river's name descends from the Miami-Illinois word the French record renders Theakiki, anglicised to Kankakee; and one spelling is disposed of expressly, against the assembly risk the audit flagged — the "Kankekee" of the 1828 treaty calls quoted in the land file is period spelling inside quotation, not a second name with a record, and no rename may be harvested from it. The fuller sequence of earlier names, treaty by treaty, stands in the treaty and survey records as the article's named residue. The township's documented waters remain its lakes — Spicer and Lancaster, carried whole as park ground — and their presence is not river coverage, nor counted as it.

Sources:

1. The Geological Survey / basin record of the Kankakee (source, course, 133 miles, the Des Plaines confluence, the natural ~240-mile course), read for this run.
2. This build's The Land (the 1828 treaty calls, with the 'Kankekee' spelling) and this history (the lakes as park ground; the pointer this article answers).