| 39477 | April 6 | Event | 1970 – Newhall massacre: Four California Highway Patrol officers are killed in a shootout. |
| 39478 | April 6 | Event | 1972 – Vietnam War: Easter Offensive: American forces begin sustained air strikes and naval bombardments. |
| 39479 | April 6 | Event | 1973 – Launch of Pioneer 11 spacecraft. |
| 39480 | April 6 | Event | 1973 – The American League of Major League Baseball begins using the designated hitter. |
| 39451 | April 6 | Event | 1866 – The Grand Army of the Republic, an American patriotic organization composed of Union veterans of the American Civil War, is founded. It lasts until 1956. |
| 39452 | April 6 | Event | 1869 – Celluloid is patented. |
| 39453 | April 6 | Event | 1888 – Thomas Green Clemson dies, bequeathing his estate to the State of South Carolina to establish Clemson Agricultural College. |
| 39454 | April 6 | Event | 1893 – Salt Lake Temple of The Church of Jesus Christ of Latter-day Saints is dedicated by Wilford Woodruff. |
| 39455 | April 6 | Event | 1895 – Oscar Wilde is arrested in the Cadogan Hotel, London after losing a libel case against the Marquess of Queensberry. |
| 39456 | April 6 | Event | 1896 – In Athens, the opening of the first modern Olympic Games is celebrated, 1,500 years after the original games are banned by Roman emperor Theodosius I. |
| 39457 | April 6 | Event | 1909 – Robert Peary and Matthew Henson reach the North Pole. |
| 39458 | April 6 | Event | 1911 – During the Battle of Deçiq, Dedë Gjon Luli Dedvukaj, leader of the Malësori Albanians, raises the Albanian flag in the town of Tuzi, Montenegro, for the first time after George Kastrioti (Skanderbeg). |
| 39459 | April 6 | Event | 1917 – World War I: The United States declares war on Germany (see President Woodrow Wilson's address to Congress). |
| 39460 | April 6 | Event | 1919 – Mohandas Karamchand Gandhi orders a general strike. |
| 39461 | April 6 | Event | 1923 – The first Prefects Board in Southeast Asia is formed in Victoria Institution, Malaysia. |
| 39462 | April 6 | Event | 1924 – First round-the-world flight commences. |
| 39463 | April 6 | Event | 1926 – Varney Airlines makes its first commercial flight (Varney is the root company of United Airlines). |
| 39464 | April 6 | Event | 1929 – Huey P. Long, Governor of Louisiana, is impeached by the Louisiana House of Representatives. |
| 39465 | April 6 | Event | 1930 – Gandhi raises a lump of mud and salt and declares, "With this, I am shaking the foundations of the British Empire," beginning the Salt Satyagraha. |
| 39466 | April 6 | Event | 1936 – Tupelo–Gainesville tornado outbreak: Another tornado from the same storm system as the Tupelo tornado hits Gainesville, Georgia, killing 203. |
| 39467 | April 6 | Event | 1941 – World War II: Nazi Germany launches Operation 25 (the invasion of Kingdom of Yugoslavia) and Operation Marita (the invasion of Greece). |
| 39468 | April 6 | Event | 1945 – World War II: Sarajevo is liberated from German and Croatian forces by the Yugoslav Partisans. |
| 39469 | April 6 | Event | 1945 – World War II: The Battle of Slater's Knoll on Bougainville comes to an end. |
| 39470 | April 6 | Event | 1947 – The first Tony Awards are presented for theatrical achievement. |
| 39471 | April 6 | Event | 1957 – Greek shipping tycoon Aristotle Onassis buys the Hellenic National Airlines (TAE) and founds Olympic Airlines. |
| 39472 | April 6 | Event | 1962 – Leonard Bernstein causes controversy with his remarks from the podium during a New York Philharmonic concert featuring Glenn Gould performing Brahms' First Piano Concerto. |
| 39473 | April 6 | Event | 1965 – Launch of Early Bird, the first commercial communications satellite to be placed in geosynchronous orbit. |
| 39474 | April 6 | Event | 1965 – The British Government announces the cancellation of the TSR-2 aircraft project. |
| 39475 | April 6 | Event | 1968 – In Richmond, Indiana's downtown district, a double explosion kills 41 and injures 150. |
| 39476 | April 6 | Event | 1968 – Pierre Elliott Trudeau wins the Liberal Leadership Election, and becomes Prime Minister of Canada soon after. |