Greetings Charlie,
Because urban yard trees add significant value to property and home, I would strongly urge you to contact a certified arborist to conduct an on-site assessment of your trees. This is your best course of action in this situation!
There are two ways to find a certified arborist to assist you (1) check your local yellow pages under arborist, tree service, tree care specialist, landscape, lawn, or (2) visit the one of two websites http://www.illinoisarborist.org/CertifiedArborists.htm http://www.isa-arbor.com/findArborist/findarborist.aspx
This should get you started!