The Des Plaines River, the Chicago Sanitary and Ship Canal, and railroad freight lines triggered Joliet's growth as a center of commerce and industry. The canal's Brandon Road Locks, to the south of Joliet, are among the largest in the world, and the canal continues to carry many millions of tons of barge traffic annually through the city. Joliet once supplied limestone (Joliet/Lemont) to much of the nation and was once a major center for steel production. Although Joliet was named in honor of Louis Jolliet, the French-Canadian explorer who visited the area in 1673, it was incorporated in 1837 as Juliet, companion to the nearby town of Romeo (now renamed Romeoville).