The Atchafalaya River, whose name means "long river" in Choctaw, is a 137-mile river that begins near Simmesport at the confluence of the Red River with the Mississippi and flows south past Morgan City into Atchafalaya Bay in the Gulf of Mexico. The fifth largest river in North America by discharge, it is a heavily used navigation route that saves vessels almost 172 miles between the Mississippi above Old River Lock and the Gulf Intracoastal Waterway in southern Louisiana, and its lower course near the Gulf has made the area a popular shipping departure point despite persistent challenges from sedimentation and the close spacing of three bridges. After offshore oil drilling off the coast of Morgan City began in the 1940s, construction materials were often transported down the river for Gulf drilling until Alden J. “Doc” LaBorde developed a movable, submersible barge that could carry drilling equipment and be floated from one location to another. Named for Charles H. Murphy's father and backed by his inspiration and initial funding, Mr. Charlie entered service in 1954 as the first rig of its kind, housing up to 58 workers on a 220-foot by 85-foot barge with a 60-foot-high platform, and it made oil drilling easier and more economical by submerging its weighted base onto the Gulf floor during operations. Subcontracted by Shell Oil and other companies from Ocean Drilling and Exploration Company, Mr. Charlie remained in use until deeper-water exploration made its 40-foot depth limit obsolete, and after drilling its last well in 1986 it became a museum and training site for oilfield workers; in 2012, the American Society of Mechanical Engineers named Mr. Charlie Oil Rig a Historic Mechanical Engineering Landmark.