Jean Heffer offers a history of the Pacific as a "frontier" of the United States using economics, politics, and culture as his central areas of consideration. Heffer focuses on three major chronological periods. The first period stretches from 1784, the year the first ship flying the American flag reached China, to 1867, the eve of the Civil War. During this period, America's presence was expanding throughout the entire ocean. The second period, from 1868 to Pearl Harbor in 1941, witnessed a simultaneous contraction of the area within which various American interests were active, and a gradual integration of the frontier region. Finally, World War II marks the beginning of the third period, which concludes in 1994, during which, Heffer argues, the entire Pacific becomes an "American lake" and the former frontier begins to disappear.