October 20
1740 - Maria Theresa became the ruler of Austria, Hungary and Bohemia with the death of her father, Holy Roman Emperor Charles VI.
1774 - The new Continental Congress, the governing body of America’s colonies, passed an order proclaiming that all citizens of the colonies "discountenance and discourage all horse racing and all kinds of gaming, cock fighting, exhibitions of shows, plays and other expensive diversions and entertainment."
1803 - The U.S. Senate approved the Louisiana Purchase.
1818 - The U.S. and Great Britain established the boundary between the U.S. and Canada to be the 49th parallel.
1827 - The Battle of Navarino took place during the Greek War for Independence.
1873 - A Hippodrome was opened in New York City by showman Phineus T. (P.T.) Barnum.
1892 - The city of Chicago dedicated the World's Columbian Exposition.
1903 - A joint commission ruled in favor of the U.S. concerning a dispute over the boundary between Canada and the District of Alaska.
1910 - A baseball with a cork center was used in a World Series game for the first time.
1930 - "The Adventures of Sherlock Holmes" debuted on NBC radio.
1935 - Mao Zedong arrived in Hanoi after his Long March that took just over a year. He then set up the Chinese Communist Headquarters.
1942 - Pierre Laval told the French labor that they must serve in Germany.
1944 - Allied forces invaded the Philippines.
1944 - During World War II, the Yugoslav cities of Belgrade and Dubrovnik were liberated.
1947 - Hollywood came under scrutiny as the House Un-American Activities Committee opened hearings into alleged Communist influence within the motion picture industry.
1952 - The Mau Mau uprising against white settlers began in Kenya.
1955 - "No Time for Sergeants" opened on Broadway at the Alvin Theatre. The show starred Andy Griffith and Don Knotts made his Broadway debut. The last show was on September 14, 1957.
1957 - Walter Cronkite began hosting "The 20th Century." The show aired until January 4, 1970.
1968 - Jackie Lee Bouvier Kennedy married Aristotle Onassis.
1979 - The John F. Kennedy Library in Boston was dedicated.
1984 - The U.S. State Department reduced the number of Americans assigned to the U.S. embassy in Beirut, Lebanon.
1993 - Attorney General Janet Reno warned the TV industry to limit the violence in their programs.
1994 - The website WhiteHouse.gov was launched.
1995 - Britain, France and the U.S. announced a treaty that banned atomic blasts in the South Pacific.
2003 - A 40-year-old man went over Niagara Falls without safety devices and survived. He was charged with illegally performing a stunt.
2009 - European astronomers discover 32 exoplanets.
