October 20

1774 – The Continental Association, a nonconsumption and nonimportation agreement against the British Isles and the British West Indies, is adopted by the First Continental Congress.

1803 – The Senate ratifies the Louisiana Purchase.

1818 – The Convention of 1818 is signed between the United States and the United Kingdom, which settles the Canada–United States border on the 49th parallel for most of its length.

1941 – Thousands of civilians in German occupied Serbia are murdered by Nazi soldiers in the Kragujevac massacre.

1944 – Liquefied natural gas leaks from East Ohio Gas Company storage tanks in Cleveland and then explodes, leveling 30 blocks and killing 130 people.

1947 – The House Un-American Activities Committee begins its investigation into Communist infiltration of the Hollywood film industry

1973 –  President Nixon fires Attorney General Elliot Richardson and Deputy Attorney General William Ruckelshaus after they refuse to fire special prosecutor Archibald Cox, who is finally fired by Solicitor General, Robert Bork.

1976 – On the Mississippi river in St. Charles Parish, Louisiana, the Luling–Destrehan Ferry George Prince is struck by the Norwegian tanker SS Frosta, killing 78 of the 96 passengers and crew aboard the ferry with no casualties on the tanker.

1977 – A L & J Company owned Convair CV-240 aircraft, leased by the rock band Lynyrd Skynyrd, runs out of fuel enroute to Baton Rouge Louisiana and crashes while the pilots attempt an emergency landing in a field near Gillsburg, Mississippi, killing 6 of the 24 passengers aboard, 3 of them, members of the band.

1981 – Two police officers and a Brink’s armored car guard are killed during an armed robbery carried out by members of the Black Liberation Army and Weather Underground in Nanuet, New York.

1991 – Starting from an incompletely extinguished grass fire in the Berkeley Hills, a massive firestorm breaks out on the hillsides of northern Oakland, and southeastern Berkeley, California killing 25 people and destroying more than 3,000 homes, apartments and condominiums.

2003 – The Sloan Great Wall, a cosmic galactic filament structure formed by a giant wall of galaxies, is discovered within the region of the constellations Corvus, Hydra and Centaurus, by astronomers studying data from the Sloan Digital Sky Survey at Princeton University

2011 – Libyan rebel forces capture and kill dictator Muammar Gaddafi in his hometown of Sirte.