On this day, April 20 ...

1999: The Columbine High School massacre takes place in Colorado as two students shoot and kill 12 classmates and one teacher before taking their own lives.

Also on this day:

1898: The United States moves closer to war with Spain as President William McKinley signs a congressional resolution passed the day before recognizing Cuban independence and authorizing U.S. military intervention to achieve that goal.

The United States moves closer to war with Spain as President William McKinley signs a congressional resolution passed the day before recognizing Cuban independence and authorizing U.S. military intervention to achieve that goal. 1914: The Ludlow Massacre takes place when the Colorado National Guard opens fire on a tent colony of striking miners.

The Ludlow Massacre takes place when the Colorado National Guard opens fire on a tent colony of striking miners. 1938: “Olympia,” Leni Riefenstahl’s documentary about the 1936 Berlin Olympic games, is first shown in Nazi Germany.

“Olympia,” Leni Riefenstahl’s documentary about the 1936 Berlin Olympic games, is first shown in Nazi Germany. 1971: The U.S. Supreme Court unanimously upholds the use of busing to achieve racial desegregation in schools.