Proof of residency is all that's needed.
The aquarium also extended its hours to 9 p.m. on Mondays, Wednesdays and Thursdays with special events such as Jazzin' at the Shedd.
Capacity is limited. Aquarium officials recommend reserving your free admission online, which requires a $3 processing fee.
Free Illinois resident days will be available on Oct. 3 and 10.
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