The Story of American Expansionism

American history is in trouble—the discipline, that is. The share of college students who major in history has fallen by two-thirds since the early 1970s. Only 40% of Americans—27% under age 45—“demonstrate a basic understanding of American history,” according to a recent Woodrow Wilson Foundation survey. One reason for the history recession: Much of the work produced today is too narrow and esoteric to interest nonspecialists.

So Northwestern University history professor Daniel Immerwahr deserves credit for attempting a sweeping,...