1950s: Of a total U.S. population of close to 164.3 million in 1955, around 7.4 million are aged between 65 and 79, or 4.5 percent.

1990s: Of a total U.S. population of 273.9 million in 1998, just over 18 million are aged between 65 and 79, or 6.6 percent.

1950s: In 1956, the Supreme Court rules that segregated transportation systems are illegal.

1960s: In 1960, the Supreme Court rules that segregation in certain public facilities is illegal.

1970s: In 1971, the Supreme Court upholds affirmative actions programs in schools and businesses.

1990s: In 1996, the Supreme Court hears a case involving allegations that federal prosecutors in Los Angeles selectively pursued and charged blacks in crack cocaine cases. The Court finds that the African-American defendants are unable to prove the allegations, so the guilty charge stands.

1950s and 1960s: African Americans stage numerous boycotts, marches, and sit-ins to protest segregation laws in the South.

1990s: Since passage of the...