Kellogg’s came up with the idea for Pop-Tarts in 1964, but company leaders weren’t sure how to implement it. They put a call in to Bill Post, a Grand Rapids resident who was working as a plant manager for Keebler. Post and his team got to work figuring out how to manufacture two sheets of dough with filling in between. The trial-and-error process took a few months and involved things that were considered "crazy" at the time, like raising up extremely heavy equipment and placing one sheeter over another, but eventually, Post and his team were successful. Kellogg’s first sold their Pop-Tarts in Cleveland, Ohio. The four original flavors were Strawberry, Blueberry, Brown Cinnamon Sugar, and Apple Currant. All four were unfrosted. In November 1964, Pop-Tarts hit grocery store shelves nationally. The product stock actually sold out, proving that Kellogg's was definitively successful in beating their then-competitor, Post's Country Squares. (Note that here, Post refers to the company known as Post Consumer Brands, not Bill Post, the mastermind behind Pop-Tarts.) In 1967, the first frosted Pop-Tarts — which were once again brought to life by Bill Post and his team — debuted and included four additional flavors: Dutch-Apple, Concord Grape, Raspberry, and Brown Sugar-Cinnamon. Sprinkles debuted the following year. By 1973, there were 19 different varieties available; today, there are over 30 different Pop-Tart flavors to choose from. The company introduced their iconic “Crazy Good” tagline in 2004 and in 2018, they debuted a line of minis called Pop-Tarts Bites. Today, Pop-Tarts remain a fan favorite all across America. The company reports that the Frosted Strawberry and Frosted Brown Sugar Cinnamon are the two most popular flavors.