Concrete gates have been controlling about 70 percent of the Mississippi River's flow toward New Orleans and Baton Rouge since 1963. The river naturally tends to flow toward the Atchafalaya, a shorter and steeper path to the Gulf of Mexico. If these structures were to fail, it could have significant economic consequences for Louisiana's two largest ports. South of where the Mississippi meets the Red River, the concrete gates decide each day how much of the river's flow goes toward the Atchafalaya. The division is set at 70 percent for the Mississippi and 30 percent for the Atchafalaya, measured at a point known as Red River Landing. This 70 percent flow helps maintain the channel that passes through Baton Rouge and New Orleans. However, the Mississippi River has been trying to change course since the middle of the 20th century. Initially, high water levels were thought to be the cause, but later, the Gulf of Mexico's erosion of the delta was considered. However, the structure, built by the U.S. Army Corps of Engineers, offers no protection against these factors. The river's main competitor for its course is the Atchafalaya, which provides a shorter and steeper path to the Gulf. After the removal of a large obstruction blocking the Atchafalaya in 1840, the Old River has increasingly flowed westward, and by 1880, it rarely flowed eastward. Engineers eventually estimated that without intervention, the Mississippi could shift into the Atchafalaya as early as 1990. The Old River, which is 11 kilometers long and connects the Mississippi to the Red River, is where the Corps placed its gates. Since then, the Atchafalaya has received 30 percent of the combined flow of the Red River and the Mississippi. In 1973, the structure was nearly overwhelmed during a flood. The force of the water damaged the concrete and almost caused the gates to fail. To relieve pressure, the Morganza spillway was opened. A neighboring structure, the Old River Control Auxiliary Structure, later added gates designed for major floods. The New York Times reported in 1987 that the project had already cost 500 million dollars, noting that the cost was still rising. This figure was from before the Sidney A. Murray Jr. hydroelectric plant, completed in 1990 and the last element of the complex. The complex now includes four structures. Journalist John McPhee wrote a detailed narrative on this struggle, Atchafalaya, which was published in The New Yorker on February 23, 1987. He described the effort to keep the river in a channel it wants to leave, likening it to an ordinary construction site against the elements. If the structure were to fail, the Mississippi would create a new delta south of Morgan City. The channel serving Baton Rouge and New Orleans would lose a significant portion of its flow, with serious economic consequences for these two ports. Some observers worry that the water flow might become too shallow for deep-sea ships and that saltwater could rise as far as Baton Rouge. The Atchafalaya ports, however, are not equipped to handle large barges, and adapting them would take months, or even years. Time is not on the side of engineers. According to an analysis by Weather Underground after the 2019 flood, the Mississippi River bed is about 17 to 19 feet (5 to 6 meters) higher than that of the Atchafalaya for typical flows. This gap increases as floods scour the bottom of the Atchafalaya. The two highest floods recorded at the structure were in 2011 and 2019. The 70/30 flow split is not a natural law: according to an analysis by Responsible Alpha, it was Congress that imposed this division on the Corps of Engineers. The river itself did not agree to it.