From the August 27, 2015, Chicago Tribune "Midewin prairie preparing for arrival of 30-35 bison" by Susan DeMar Lafferty.
Until this past year, some 200 years had passed since bison roamed freely in Illinois prairies, but at the Midewin National Tallgrass Prairie, some 30-35 will be doing that roaming this fall. The staff of the U.S. Forest Service have been planning for this the past two years and they will be grazing on 1,200 acres of grassland where they will do their part to restore the natural prairie.
Midewin was created in 1996 from the Army's now-closed Joliet Arsenal, located about 60 miles southwest of Chicago in Will County. This is right on Route 66.
They hope the bison will have an appetite for the grasses and devour enough so that other plants can thrive which will attract a more diverse population of birds and insects.