1930s: Hitler's Nazi party takes over in Germany; Mussolini's Fascists rule Italy, and the world is plunged into war.

1960s: The world is divided into two power blocs, the United States and the Soviet Union, and the cold war is at its height. Germany remains divided into East Germany, which is communist, and West Germany, which is a member of NATO.

Today: A reunited Germany is at the heart of the European Union; the Soviet Union is a thing of the past, and the United States is the sole remaining superpower.

1930s: A voyage from Mexico to Europe in a passenger/freight ship like the Vera takes twenty-six days. Ocean liners are the most common form of long-distance transportation across the ocean.

1960s: The bulk of long-distance travel is by jet aircraft. Many of the large ocean liners are retired; new passenger ships are...