LONGLISTED FOR THE 2019 NATIONAL BOOK AWARD FOR NONFICTION From a Pulitzer Prize finalist, a new and eye-opening interpretation of the meaning of the frontier, from early westward expansion to Trump's border wall. Ever since this nation's inception, the idea of an open and ever-expanding frontier has been central to American identity. Symbolizing a future of endless promise, it was the foundation of the United States' belief in itself as an exceptional...