Six Flags ONLY accepts card & mobile payments onsite. This includes parking. There are cash-to-card devices inside the park. These kiosks providing patrons with VISA cards in various locations throughout the park. The VISA cards are not exclusive to Six Flags and its sister theme parks. You can also utilize personal credit and debit cards or …

https://www.visitlakecounty.org/six-flags-great-america-ticket-guide