The entry of the United States into World War II caused vast changes in virtually every aspect of American life. Millions of men and women entered military service and saw parts of the world they would likely never have seen otherwise. The labor demands of war industries caused millions more Americans to move--largely to the Atlantic, Pacific, and Gulf coasts where most defense plants located. When World War II ended, the United States was in better economic condition than any other country in the world.

Read the first paragraph of the Library of Congress’s article “The Post War United States, 1945–1968” to answer the question.
4. Select the highlighted phrase that cites a cause of demographic changes in the country during the wa