1. On October 20, 1977, the Seattle Mariners played their last home game at the Kingdome before moving to their new stadium, Safeco Field, in 1999.

2. In 1861, the Union Army led by General George B. McClellan seized Munson's Hill, a strategic location overlooking Washington D.C. during the American Civil War.

3. October 20, 1939 saw the opening of the New York World's Fair Pavilion in Washington D.C., featuring exhibits in science, engineering, and the arts.

4. In 1962, President John F. Kennedy addressed the nation from the White House to announce the discovery of Soviet missiles in Cuba, leading to the Cuban Missile Crisis.

5. On this day in 1918, Washington State College (now Washington State University) beat the University of Washington in the first Apple Cup football game, beginning a long-standing rivalry between the two universities.