In 2026, the answer is "Yes" in terms of corporate ownership, but "No" in terms of history. Following the 2024 merger between Six Flags and Cedar Fair, both parks are now operated by the same parent company, Six Flags Entertainment Corporation. However, they were originally two different properties. Six Flags Great America (located in Gurnee, Illinois) has always been a flagship Six Flags park. California's Great America (located in Santa Clara, California) was originally built by the same developer (Marriott) but was owned by Cedar Fair for decades before the merger. Interestingly, in 2026, the California park is operating under a long-term "land-lease" and is scheduled to permanently close within the next few years as the land was sold to a developer, whereas the Illinois park remains a permanent fixture of the Six Flags portfolio. So, while you can now use a "Legacy Pro" season pass at both locations, they are distinct parks with different ride lineups and historical identities.