Wikipedia:Selected anniversaries/December 20
This is a list of selected December 20 anniversaries that appears on the "On this day" section of the Main Page. To suggest a new item, in most cases you can be bold and edit this page. Please read the selected anniversaries guidelines before making your edit. However, if your addition might be controversial, or on a day that is or soon will be on the Main Page, please post your suggestion on the talk page instead.
Please note that the events listed on the Main Page are chosen based more on relative article quality and to maintain a mix of topics, not based solely on how important or significant their subjects are. Only 5–6 events are posted at a time and thus not everything that is "most important and significant" can be listed. In addition, an event is not generally posted this year if it is also the subject of the scheduled December 20, 2017 featured article or the December 20, 2017 featured picture.
To report an error when this appears on the Main Page, see Main Page errors. Please remember that this list defers to the supporting articles, so it is best to achieve consensus and make any necessary changes there first.
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Flag of Concelho de Macau, one of the two concelhos of Macau under Portuguese rule
|1803 – As part of the Louisiana Purchase, New Orleans in the French territory of Louisiana was officially transferred to the United States.||refimprove section|
|1917 – The Cheka, the first Soviet secret police, was established by a decree issued by Vladimir Lenin.||refimprove section|
|1941 – World War II: The Flying Tigers of the Chinese Air Force engaged in its first combat missions.||refimprove section|
|1946 – Frank Capra's popular Christmas film It's a Wonderful Life was first released in New York City.||refimprove section|
|1957 – The first flight of the Boeing 707, the first commercially successful jet airliner, took place.||refimprove section|
|1973 – Spanish Prime Minister Luis Carrero Blanco was assassinated by a bomb planted by members of the Basque nationalist and separatist group ETA.||needs more footnotes|
|1989 – American forces invaded Panama to overthrow the government of Manuel Noriega.||refimprove section|
- 1951 – Experimental Breeder Reactor I near Arco, Idaho, United States, became the world's first electricity-generating nuclear power plant when it produced sufficient electricity to illuminate four 200-watt light bulbs.
- 1968 – The Zodiac Killer murdered the first of his five confirmed victims in Vallejo, California, a case which remains unsolved.
- 1980 – NBC aired the American football match between the New York Jets and the Miami Dolphins without announcers.
- 1987 – The deadliest peacetime maritime disaster in history occurred when the MV Doña Paz sank after colliding with an oil tanker on the Tablas Strait in the Philippines, resulting in an estimated 4,000 deaths.
- 1995 – American Airlines Flight 965 crashed into a mountain in Buga, Colombia, killing 151 passengers and 8 crew members.
- 1995 – As per the Dayton Agreement that ended the Bosnian War, the NATO-led IFOR began peacekeeping operations in Bosnia and Herzegovina.
- 2005 – US district court Judge John E. Jones III ruled against mandating the teaching of "intelligent design" in his ruling of Kitzmiller v. Dover Area School District.
- 2007 – Pablo Picasso's Portrait of Suzanne Bloch was stolen from the São Paulo Museum of Art and recovered about three weeks later.
- 1860 – South Carolina became the first of eleven slave states to secede from the United States, leading to the eventual creation of the Confederate States of America and later the American Civil War.
- 1955 – Cardiff (Cardiff City Hall pictured) was proclaimed as the capital of Wales.
- 1971 – Two groups of French doctors involved in humanitarian aid merged to form Médecins Sans Frontières.
- 1988 – The United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances governing international cooperation against the illegal drug trade was signed in Vienna.
- 1999 – Portugal transferred sovereignty of Macau, which it had administered since the mid-16th century, to China.