How much did the U.S. national debt grow during World War II? August 26, 2011 by Pamela Landy · Filed Under: American History The U.S. national debt grew about sixfold during World War II. In 1940, the national debt was $43 billion. At the end of World War II, it was $258.7 billion. Related PostsHow much has the U.S. National Debt increased over the nation’s history?How much money was raised from war bonds during World War II?How large was the first national debt in the U.S.?Has the U.S national debt ever been fully paid off?How much credit card debt does the average American owe?