A recent report from Brown University's Costs of War project estimates that the number of people displaced in wars involving the United States since 9/11 is 37 million, though the actual number could be as high as 59 million. The lower estimate is equivalent to removing nearly all the residents of California or the total populations of Texas and Virginia combined.
In historical terms, it represents the highest level of displacement of any war or disaster since the start of the 20th century except for the Second World War which saw somewhere between 30 and 64 million people forced from their homes. By comparison "only" 10 million people were displaced during World War I while the Vietnam War saw 13 million displaced.
