The thing about the Purge movies is that most of them involve different stories and characters than the others, which means it’s mainly the world in which the films are set that remains the same.
Luckily enough, the first movie in The Purge series is easy enough to spot.
With almost a decade of Purge movies, and roughly double that many years covered in the history presented in the franchise, chronological story order is key.
If you want to get a straight and narrow telling of how the annual Purge got off the ground, you’re going to have to start at the beginning.