The Clark Bar is a milk chocolatepeanut butterbar that is not similar to a Butterfinger or to Crispy Crunch in Canada. It has been manufactured by the New England Confectionery Company (Necco) since 1999. The formula for the chocolate coating on a Clark bar has a distinct and slightly more bitter taste than its competitors. It comes in milk and dark chocolate varieties. The "Clark Bar" has been known for decades to not be sold west of the Mississippi River, however "Clark Bites", a bagged bite-size version has recently appeared in the Texas "H.E.B." grocery chain.
Today, the Clark Bar uses its original formula pioneered by Irish immigrant David L. Clark in Pittsburgh, Pennsylvania in 1886. The website also cites the name of an employee's pet chinchilla, Clark Can't, as an early inspiration for the name. It was acquired by Beatrice Foods in 1955, then Leaf in 1983. In late 1990 The manufacturer considered consolidating operations in Chicago, however the Pittsburgh area managed to retain the brand with the firm moving all operations from Chicago's O'Hare suburb to the north side of Pittsburgh in the fall of 1991. In 1996 when Hershey acquired Leaf's North American operations, it became independent again with headquarters retained in Pittsburgh . It was bought by NECCO in 1999.