Given the location - images having originated nr. the Wiscosin border - I think canicularis is a good call.

Based on the most recent collection endeavors, the 2 most common species in that vicinity are linnei & canicularis. The cicada in these pic's does not seem to possess the wing shape and wing length to body ratio typical of linnei in that area (esp. females as pictured here), so I'm inclined to go along with canicularis.

T. pruinosus is common across much of Illinois to the south of that locality, but drops off in numbers across n. IL and is often absent from many adj. areas to this siting.

You're certainly correct about it being newly emerged, as I'd watched it emerge the previous night in a jar. I will post a few pictures of that as well in hopes that they will help.