Well Jason's reply that it is not a unlawful thing to do when placing a for sale sign in front of a property may apply in Chicago I don't know.But in the states I've done business it is. Some were state laws some were local, but it allowed you to be fined if you didn't have the express written permission of the owner before the sign was placed, and it was also a misdemeanor on your record.
That being said, I've done it several times and it works. The couple times I was called on it I said so that's where that sign went, I lost one from 123 main street, probably kids having fun that happens once in awhile in my business,
Where can I pick it up and I want to thank you for calling me, most people won't bother so I really appreciate it.
I pick it up and bring a box of chocolates as a thank you which opens the flow of info. Try it, it works.