1494 – On his second expedition to the New World, Columbus discovered Jamaica.
1776 – Rhode Island becomes the first American colony to renounce allegiance to King George III.
1886 – Haymarket affair: A bomb is thrown at policemen trying to break up a labor rally in Chicago, killing eight and wounding 60. The police open fire into the crowd.
1904 – The United States begins construction of the Panama Canal.
1942 – The Battle of the Coral Sea began. It was a turning point for the Allies in World War II, with Japan losing 39 ships and the United States one.
1953 – Ernest Hemingway wins the Pulitzer Prize for The Old Man and the Sea.
1970 – The Ohio National Guard, sent to Kent State University, opens fire killing four unarmed students and wounding nine others.
1979 – Margaret Thatcher becomes the first female Prime Minister of the United Kingdom.
1989 – Iran-Contra Affair: Former White House aide Oliver North is convicted of three crimes and acquitted of nine other charges; the conventions are later overturned on appeal.
1998 – A federal judge sentences “Unabomber” Theodore Kaczynski to four life sentences plus 30 years after Kaczynski accepts a plea agreement sparing him from the death penalty.