To follow on Gene's post, there never was a Cicero Mob. The Capone Mob moved into Cicero in 1924 and they have been there ever since (99% correct approximation).

There is only the Chicago Outfit in Northern Illinois since 1934. They have run Cicero for years, although it has declined as a
Mob influenced/active area due to ethnic change recently.

The "4020" stamped chip you are probably inquiring about is certainly from the 4020 Club at 4020 W. Ogden about a mile east of the Cicero boundaries. Same place as the chips stamped "4020 Club"

John