Six Flags Great America will mark its actual anniversary date with a 50th Anniversary Day Bash on Friday, May 29, at the Gurnee, Illinois park.
The day starts at 11 a.m. in Hometown Square, where the park is planning a kickoff celebration with party hats and a free sweet treat while supplies last. The birthday program runs one day only, on the date tied to the park's 1976 debut.
Four of a Kind, the park's original quartet from 1976, is returning for performances throughout the park. The group started as high school friends from Greendale, Wisconsin, then spent two college summers working and performing at Great America.
The Emporium opens May 29 with exclusive 50th anniversary merchandise. Inside the same shop, the Legacy Museum will display artifacts from the park's first five decades.
The night closes with fireworks at 9:30 p.m. It is one of several anniversary fireworks dates for the park this season, joining the May 24, July 4, and Sept. 6 fireworks dates already announced in the park's 50th season preview.
The one-day bash comes before the larger 50th Anniversary Celebration, which runs June 20 through Aug. 9. That longer summer event includes 10 p.m. park hours, a new nighttime spectacular with a parade and drone show, anniversary food and drinks, the 50th Anniversary Legacy Store inside Emporium, and commemorative bricks for the Great America Legacy Path near Orleans Place.
Six Flags Great America first opened in 1976 as Marriott's Great America. The 2026 season is leaning into that history with classic park music, Carousel Columbia nods, anniversary merchandise, and the kind of one-night fireworks finale that gives a birthday date its own crowd draw.