In 1803, the United States purchased 828,000 square miles of land from France at a price of approximately three cents per acre, dramatically altering the young nation's geography and its political future. President Thomas Jefferson had struggled for three years over the purchase, which many believed to be unconstitutional, during which time the land changed hands between the French and the Spanish. In perhaps the nation's most formative development since the Revolutionary War, the deal secured the U.S. territory that would become fifteen new states, sparked intense public argument about the...