On this day in 1963, Alcatraz, a federal penitentiary on an island in San Francisco Bay, closed.
On this day in 1965, Dr. Martin Luther King, Jr. led 3,200 people on the start of the third and finally successful civil rights march from Selma to Montgomery, Alabama.
On this day in 1980, US President Jimmy Carter announced a United States boycott of the 1980 Summer Olympics in Moscow to protest the Soviet war in Afghanistan.
On this day in 1990, Namibia became independent after 75 years of South African rule.
And on this day in 2006, the social media site Twitter was founded.