The first stage brings you to Kingston Park. Nearby, you will find a "rules and regulations" type of sign from the park district. Use this to figure out the latitude. You'll also be using some other nearby items to figure the longitude.
The final stage is located at N 41° 31.ABC , W 087° 48.DEF
AB = The number of red letters on the top sign + 31 ; C = The number of red words on the middle sign.
DE = The posted speed limit on Kingston Dr. + 18 ; F = The number of swings + the number of sand digging toys.
You can check your answers for this puzzle on GeoChecker.com.