With the Shedd Aquarium's Wild Reef as a backdrop, Gov. Pat Quinn signed a law banning the sale, trade or distribution of shark fins.
Illinois becomes the first inland state to adopt such a ban. Lawmakers who pushed for it have said Chicago's Chinatown has been a hub for the sale of shark fin in the Midwest.
Quinn says the ban will aid global efforts to prevent the collapse of shark populations.
Shark fins are typically used in soup and other Asian cuisine. After harvesting their fins, many sharks are thrown back into the ocean to bleed to death or drown.
Shedd Aquarium President and CEO Ted Beattie applauded the ban and said millions of sharks are killed each year, many only for their fins.
Quinn signed the law Sunday.