Six Flags Great America is now officially open for the 2026 season, and the park quietly made a big change to one of its policies. The park, in suburban Gurnee, has a number of policies and codes of conduct listed online, including dress codes, behavior policies, and special notices to parents and guardians. It also has a large banner at the top of its site that says “Chaperone Policy In Effect.” “Because Six Flags is a family park, we expect gu…