Many cities do not have straight boundary lines. My search came up with a school district 99 boundaries map. I called the District office to verify that that map was indeed the entire city and they verified that their school district encompasses all of Cicero.
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Cicero Ave on the East (Between 16th ave and 22nd the boarder stretches to 47th Ave)
Lombard on the West
Pershing on the South
Roosevelt on the North
I I hope this helps with your search.