Prior to working on the series, series creator Alex Hirsch's primary inspiration growing up was the popular animated sitcom The Simpsons, where he observed that "animation could be funnier than live-action. That animation didn't have to just be for kids. That it could be satirical and observational and grounded in a sense of character interaction". Hirsch graduated from the California Institute of the Arts, and was hired to work as writer and storyboard artist for the Cartoon Network series The Marvelous Misadventures of Flapjack, where he was paired up with Pendleton Ward, the creator of Adventure Time. Afterwards, he moved on to co-develop the Disney Channel animated series Fish Hooks; shortly before he pitched (and was subsequently green-lit) Gravity Falls. Hirsch says he was at the California Institute of the Arts when he turned down DreamWorks Animation executive Jeffrey Katzenberg out of a desire to work for Disney. He first coined the concept for the show in an 11-minute low-budget student film which he made at the Institute.Hirsch was called in to do a pitch for Disney Channel for a show based on the short pilot.Disney Channel bought the idea and started airing the series in the summer of 2012. The series was inspired by Hirsch's own childhood experiences with his twin sister during their summer vacations, while Stan was based on his own grandfather of the same name.
The first twelve episodes of Gravity Falls aired in a regular weekly slot on Disney Channel starting in mid-2012, but subsequent episodes were broadcast without similar regularity; it took until August 2013 to broadcast the remaining eight episodes of the first season. The second season began airing a year later in August 2014, transitioning over to Disney XD, but again without any regularity to when new episodes would be first broadcast. The first nine episodes aired from August to November 2014, the following two in February and March 2015, the next eight from July to November 2015, and the finale aired in February 2016. According to Disney XD, as each episode took about six months of work to complete, they opted against stockpiling episodes to show weekly but instead take advantage of the serial nature of the show, broadcasting each episode as it was completed and making an event out of it. On April 2, 2018, reruns of the show started airing on Disney Channel, although reruns of the show still air on Disney XD.
For their summer vacation, 12-year-old twins Dipper and Mabel Pines are dropped off from their home in Piedmont, California, to the fictitious town of Gravity Falls, Roadkill County, Oregon to spend the summer with their Great Uncle Stan Pines (often shortened to Grunkle Stan), who runs a tourist trap called the "Mystery Shack". Things are not what they seem in this small town, and with the help of a mysterious journal that Dipper finds in the forest, they begin unraveling the local mysteries. With appearances from Wendy Corduroy, Mystery Shack cashier; Soos Ramirez, a friend of Dipper and Mabel and handyman to Grunkle Stan; plus an assortment of other characters, Dipper and Mabel always have an intriguing day to look forward to.