Early 1920s: Some Americans consider the Russian Revolution an important humanitarian development. Others, however, fear it to be a communist threat to American democracy.

1926: Joseph Stalin becomes dictator of the Soviet Union. His reign of terror will last for twenty-seven years.

1991: President Mikhail Gorbachev orders the dissolution of the Soviet Union, and a new Commonwealth of Independent States is formed by the countries that formerly made up the Soviet Union.

1921: Margaret Sanger founds the American Birth Control League. Other important social changes for women include the ability to vote, to receive higher forms of education, to smoke and drink, and to wear clothes that do not restrict their movements.

Today: Women are guaranteed equal rights under the law.

1921: Approximately 900,000 immigrants enter the United States in the fiscal year ending June 30. After World War I, Americans are afraid of the influx of immigrants who are...