Question: The largest county in Oklahoma by area, gets its name from the broad rolling hills and rolling tallgrass prairie and Cross Timbers encompassing the county and surrounding areas, including portions of Mayes, Tulsa, Washington and Kay Counties, was created in what year?
Sentence (from "Midewin National Tallgrass Prairie"): The first national tallgrass prairie ever designated in the U.S. and the largest conservation site in the Chicago Wilderness region, it is located on the site of the former Joliet Army Ammunition Plant between the towns of Elwood, Manhattan and Wilmington in northeastern Illinois.
Relevant evidence: No