Late 1900s/Early 1910s: Jack Johnson becomes the first black man to hold the world heavyweight boxing championship title in 1908. When he successfully defends his title in 1910, race riots break out in the United States.

1980s: African Americans riot in Liberty City, Florida, following the acquittal of police officers accused of killing an unarmed black man.

Today: The largest protest of police brutality in New York's history occurs after police officers shoot forty-one bullets at Amadou Diallo, a black immigrant.

Late 1900s/Early 1910s: Many African Americans are denied their freedom when they are impressed into slavery by the influential Tennes-see plantation owner, Joe Turney, whose exploits are memorialized in the blues song, "Joe Turner's Come and Gone." Other blacks face severe segregation and discrimination.

1980s: Tensions escalate between South Africa's black majority and the white South African leadership, in part due to the...