1920: The African American population in the United States is about 10.5 million, or nearly 10% of the American population. The average life expectancy for African American males is 45.5 years, compared to 54.4 for whites. For females the comparable figures are 45.2 and 55.6.

Today: The African American population in the United States is about 32 million, or nearly 12% of the American population. The average life expectancy for African American males is 67.5 years, compared to about 73.4 for whites. For females the comparable figures are 75.8 and 79.6.

1920: After race riots break out in twenty-six U.S. cities in 1919, the recently rejuvenated Ku Klux Klan experiences tremendous growth in 1920, expanding to 100,000 members in twenty-seven states. According to Frederick Lewis Allen in Only Yesterday, the Klan will mushroom to 4.5 million by 1924. There are sixty-one documented lynchings of African Americans in 1920.

Today: Klanwatch is an organization founded in 1980 to monitor residual Klan terrorism. In 1986, they estimated...