Editor’s note: This is the 40th in a series of essays on the history and meaning of the American political tradition. The course of this nation’s expansion was brought almost to completion by conquest during the presidency of James K. Polk, a protégé of Andrew Jackson, who favored Jackson’s expansionist policies and followed them to the letter. He was known as “young hickory,” a chip off the old block. Polk presided over the U.S.-Mexican War (1846–48). Henry Clay, whom Polk defeated in the Presidential elec … (read more)