Floods are among the worst natural disasters in history. Often caused by storms that bring heavy rain, flooding can sometimes happen with little to no warning. In rare cases, they can even be caused by humans. This type of natural disaster can also be deadly. The worst floods in the U.S. history have killed thousands of people. Just a small amount of moving water can sweep people—and even vehicles—away. Part of The Earth's Worst Natural Disasters series, The Worst Floods on Record tells the stories of some of the worst floods that have taken place in the last two centuries.