National Pineapple Upside-down Cake Day
Look Alike Day
National Lima Bean Respect Day
Volunteer Recognition Day
April 20, 1534, Jacques Cartier began the voyage during which he discovered Canada and Labrador.
On April 20 in 1789, President George Washington arrived in Philadelphia after his inauguration to an elaborate welcome at Gray’s Ferry.
1832 – Hot Springs National Park in Arkansas was established by an act of the U.S. Congress. It was the first national park in the U.S.
U.S. Congress passed an act creating the Wisconsin Territory in 1836.
Birthday of Adolf Hitler (April 20, 1889), at Braunau, Austria; German leader of the Nazi party and dictator of Germany (1933-45).
Pierre and Marie Curie refine radium chloride in 1902.
1912 – Fenway Park opened as the home of the Boston Red Sox.
On April 20, 1916, the Chicago Cubs play their first game at Weeghman Park. The name was later called Cubs Park and, in 1926, called Wrigley Field.
The League of Nations officially dissolved on April 20, 1946, giving most of its power to the United Nations.
1962 – The New Orleans Citizens’ Council offered a free one-way ride for blacks to move to northern states and promoted a boycott of Ford Motor Co. because of its (Ford Motor Co.’s) support of the Civil Rights movement.
In Louisiana, leaders of the original Citizens’ Council included State Senator and gubernatorial candidate William Rainach (Democrat), future U.S. Representative Joe D. Waggonner, Jr., (Democrat), the publisher Ned Touchstone (Democrat), and Judge Leander Perez, (Democrat), considered the political boss of Plaquemines and St. Bernard parishes south of New Orleans.
April 20, 2010, Deepwater Horizon oil spill: A massive fire on the Deepwater Horizon drilling rig in the Gulf of Mexico killed 11 workers and caused a massive oil spill, the worst spill in US history.
Birthday of Lucretia Garfield (April 19, 1832), wife of 
1861 – Colonel Robert E. Lee turned down an offer to command the Union armies during the U.S. Civil War.
1956 – Actress Grace Kelly and Prince Rainier of Monaco were married. The religious ceremony took place April 19.
Mary Surratt was arrested on April 17, 1865 as a conspirator in Lincoln’s assassination. Sentenced to death, she was hanged on July 7, 1865, becoming the first woman executed by the United States federal government.
Cartoon characters Daffy Duck, Elmer J Fudd & Petunia Pig, debut in 1937.
Ford Mustang was introduced to the North American market in 1964.
Nolan Ryan strikes out his 3,500th batter in 1983. He ranks first all-time in strikeouts at 5,714. He struck out 15 or more players in a game 26 times, second only to Randy Johnson who had 28.
In 1908 the 
April 15, 1452 was the birthday of Leonardo da Vinci, (Leonardo di ser Piero da Vinci), Italian Renaissance polymath: painter, sculptor, architect, musician, mathematician, engineer, inventor, etc. 
1865 – Death of 
1912 – The British passenger liner RMS Titanic hit an iceberg in the North Atlantic at 23:40 (sank morning of April 15th). Titanic had an estimated 2,224 people on board; more than 1500 of them died. In accordance with existing practice, Titanic’s lifeboat system was designed to ferry passengers to nearby rescue vessels, not to hold everyone on board simultaneously.
Birthday of 
1606 – The Union Flag was adopted as the flag of English and Scottish ships.
April 11, 1814 – Napoleon Bonaparte was exiled to the island of Elba.
Apollo 13 was launched on April 11, 1970. Its three man crew were James A. Lovell, Jr., John L. Swigert, Jr., and Fred W. Haise, Jr. It was the seventh manned Moon mission in the Apollo program. The lunar landing was aborted after an oxygen tank in the service module (SM) failed two days into the mission. The crew instead looped around the Moon, and returned safely to Earth on April 17.