1916: In the United States, the women's rights movement began in earnest in the nineteenth century. Margaret Sanger opens the first birth control clinic in 1916. In 1920 the 19th Amendment gives women the right to vote. The average life expectancy for men is 53.5 years; for women it is 55 years.

Today: Women have made great strides worldwide, and their average life expectancy remains 2-3 years longer than that of men (both are expected to live well past age seventy). The Supreme Court's decision in Roe v. Wade (1973) gives women the right to choose an abortion during the first few months of pregnancy.

1916: In cities, dance halls are popular places for young men women. "Ragtime" music moves into mainstream America in 1911 when Irving Berlin writes a syncopated dance tune called "Alexander's Ragtime Band." The sheet music to the song sells more than a million copies.

Today: Rap is...