1920s: Having just experienced the devastating effects of World War I, Europe is working to rebuild its economies and infrastructures.

Today: After the fall of Communism in the 1990s, European countries form the European Union—an economic organization that brings European countries under a consistent monetary system and economic policies. The European Union today has the potential of becoming one of the strongest economic entities in the world.

1930s: Many Americans who amassed fortunes in the stock market surges of the previous decade have lost everything because of the crash of 1929.

Today: After the stock market decline of 2000 and the "dot com" crash, many of the young Americans who became rich with stock options in the 1990s have lost much of their wealth.

1930s: Although many American blacks had relocated to France to avoid the discrimination in the United States, discrimination against blacks still...