Volume thirteen of the Correspondence of James K. Polk documents a critical juncture in the history of North America. The eleventh president's letters from August 1847 to March 1848 reveal his and his correspondents' official and personal concerns during the final months of the Mexican War. The U.S. capture of Mexico City and the Treaty of Guadalupe Hidalgo redrew the continental map. Mexican land stretching from Texas to California became part of...