Arkansas is notable for its bauxite mines. Arkansas was also the first U.S. state where diamonds were found. Notable Arkansans include Bill Clinton, who was governor of Arkansas before he became the President of the United States, Sam Walton, the founder of Wal-Mart, Johnny Cash, a famous guitarist known as "The Man In Black", and Rodger Bumpass, Who voices Squidward Tentacles on the Nickelodeon show SpongeBob SquarePants.