The arrival of the pumpkin spice latte, or PSL, is considered a harbinger of autumn. But how did this famous drink get its start? In 2003, a Starbucks product manager named Peter Dukes was tasked with replicating the success of Starbucks’ seasonal Peppermint Mocha drink. He and a team of R&D workers headed into Starbucks’ top-secret “Liquid Lab” and brainstormed 20 ideas for fall latte flavors. Although the idea for a “pumpkin pie latte” didn’t make much headway when they surveyed customers online, the team included it in the final cut anyway. It was ultimately chosen to go to market, so the team got to work on the flavor by literally gathering together to eat pumpkin pie and drink espresso while analyzing the flavors. They decided to focus on pumpkin and spice as the main components of their new drink. After coming up with the perfect name – Pumpkin Spice Latte – they debuted the drink at 100 Starbucks stores in Vancouver and Washington, D.C. during the fall of 2003. It was clear that the drink was a hit, and it rolled out nationwide in fall 2004. While Starbucks did not invent the idea of a pumpkin pie latte – a similar drink had appeared at a few other coffee shops previously, including at Indiana’s J.L. Hufford Coffee and Tea Company – Starbucks is responsible for turning the drink into a bona fide phenomenon. Today, the pumpkin spice latte remains their top-selling seasonal beverage of all time and has even shown up in other industries: everything from yogurt to deodorant gets a PSL makeover each fall, and the phenomenon is so popular that it is unlikely to stop any time soon.