Today, the Clark Bar uses its original formula pioneered by Irish immigrant David L. Clark in Pittsburgh, Pennsylvania in 1886. 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.