Set off some fireworks, don a costume, prepare the feast. From revisiting the past to welcoming new beginnings, celebrations are ingrained in every culture. Some remain fixed in traditions centuries-old, while others shift as they spread to new audiences and environments. But the biggest jamborees aren’t spontaneous; it takes serious planning to support large-scale, often unpredictable, carousal. Here, we pull back the curtains, past the revelers and spectators, to reveal the infrastructure that supports a celebratory swell, the boon it brings to a local economy, and the waste it leaves behind.