There are a few options in Central & Southern Illinois for it being Woodland or Mississippian, northern Illinois over towards Lake Michigan could indicate something earlier.
On tools like that it is hard for me to put a timeline on it due to the fact that tools like that were made through out the whole time of NA occupation. Cool find.
By the knob on the end it looks to me to be a Waller Knife but I do have one I found and I dont think mine is any older than Archaic. I love finding those big flake knifes