Wikipedia:Selected anniversaries/December 20
This is a list of selected December 20 anniversaries that appear in 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 will soon 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 four to five events are posted at a time and thus not everything that is "most important and significant" can be listed. In addition, an event is generally not posted this year if it is also the subject of the scheduled featured article, featured list or picture of the day.
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.
- 1803 – As part of the Louisiana Purchase, New Orleans in the French territory of Louisiana was officially transferred to the United States.
- 1860 – South Carolina seceded from the United States, leading to the American Civil War.
- 1917 – The Cheka (emblem pictured), the first Soviet secret police, was established by a decree issued by Vladimir Lenin.
- 1951 – Experimental Breeder Reactor I near Arco, Idaho, USA, became the world's first electricity-generating nuclear power plant when it produced sufficient electricity to illuminate four 200-watt light bulbs.
- 1973 – Spanish Prime Minister Luis Carrero Blanco was assassinated by a bomb planted by members of the Basque nationalist and separatist organisation ETA.
- 1999 – Portugal transferred sovereignty of Macau to the People's Republic of China.