U.S. Army engineers have opened floodgates in Louisiana in an attempt to protect large cities along the Mississippi River.
The Morganza Spillway opened to ease pressure on Baton Rouge and New Orleans.
This is the first time in four decades the level of the Mississippi has forced the floodgate to be opened.
About 25,000 people and 11,000 buildings could be adversely affected.
The Mississippi is the third-longest river in North America and its watershed is the fourth-largest in the world.
The central United States is being hit with its worst flooding in more than 70 years.
compiled from agency reports