Most e-bikes you buy and e-bikes you build are treated like bicycles in Illinois and can go everywhere bikes go, except on sidewalks. This link is close enough.
https://www.illinoisduilawyerblawg.c...tive-illinois/
Last year, the Cook County forest preserve limited ebikes to ones that could not go over 16 mph. This year, that note is gone from their web pages.
Ebikes can be very expensive, and they can be relatively inexpensive.If you build your own, a reliable battery that won't blow up is $400 and up. Motor kits are $200-300.
I have converted a few regular bikes to ebikes. In general, it's hard to build one for less than you can buy a budget ebike. However, if you can build it, then you worry less about support/repair.
You might consider a long drive out to Plainfield to see the guy in this thread. The Aventon Pace is a $1000 bike. You could probably convert a new bike for a little less money, but it wouldn't look as good. I doubt you find anything in that price at at Kozys.
https://electricbikereview.com/forum...6/#post-195753
All of the above assumes you want a low power e-bike. You can also buy those 1000-2000W motor kits and build something that goes 30+ mph. That's not my interest. Others might talk about them.