For four decades, you could only get it (!) at one place
And that place was San Francisco's now-defunct Playland-at-the-Beach, where super-genius George Whitney birthed the It's-It in 1928.
They briefly stopped making them in the early '70s
Mostly because, well, Playland closed. In 1974, four bros realized that was the dumbest thing ever, and started remaking them in a Burlingame factory and selling them to mom-and-pop shops. Those guys were the best.