| 36661 | March 31 | Event | 1917 – The United States takes possession of the Danish West Indies after paying $25 million to Denmark, and renames the territory the United States Virgin Islands. |
| 36662 | March 31 | Event | 1918 – Massacre of ethnic Azerbaijanis is committed by allied armed groups of Armenian Revolutionary Federation and Bolsheviks. Nearly 12,000 Azerbaijani Muslims are killed. |
| 36663 | March 31 | Event | 1918 – Daylight saving time goes into effect in the United States for the first time. |
| 36664 | March 31 | Event | 1921 – The Royal Australian Air Force is formed. |
| 36665 | March 31 | Event | 1930 – The Motion Picture Production Code is instituted, imposing strict guidelines on the treatment of sex, crime, religion and violence in film, in the U.S., for the next thirty-eight years. |
| 36666 | March 31 | Event | 1931 – An earthquake destroys Managua, Nicaragua, killing 2,000. |
| 36667 | March 31 | Event | 1931 – TWA Flight 599 crashes near Bazaar, Kansas, killing eight, including University of Notre Dame head football coach Knute Rockne. |
| 36668 | March 31 | Event | 1933 – The Civilian Conservation Corps is established with the mission of relieving rampant unemployment in the United States. |
| 36669 | March 31 | Event | 1942 – World War II: Japanese forces invade Christmas Island, then a British possession. |
| 36670 | March 31 | Event | 1945 – World War II: A defecting German pilot delivers a Messerschmitt Me 262A-1, the world's first operational jet-powered fighter aircraft, to the Americans, the first to fall into Allied hands. |
| 36671 | March 31 | Event | 1949 – The Dominion of Newfoundland joins the Canadian Confederation and becomes the 10th Province of Canada. |
| 36672 | March 31 | Event | 1951 – Remington Rand delivers the first UNIVAC I computer to the United States Census Bureau. |
| 36673 | March 31 | Event | 1957 – Elections to the Territorial Assembly of the French colony Upper Volta are held. After the elections PDU and MDV form a government. |
| 36674 | March 31 | Event | 1958 – In the Canadian federal election, the Progressive Conservatives, led by John Diefenbaker, win the largest percentage of seats in Canadian history, with 208 seats of 265. |
| 36675 | March 31 | Event | 1959 – The 14th Dalai Lama, crosses the border into India and is granted political asylum. |
| 36676 | March 31 | Event | 1964 – A coup d'état in Brazil establishes a military government, under the aegis of general Castelo Branco. |
| 36677 | March 31 | Event | 1966 – The Soviet Union launches Luna 10 which later becomes the first space probe to enter orbit around the Moon. |
| 36678 | March 31 | Event | 1970 – Explorer 1 re-enters the Earth's atmosphere after 12 years in orbit. |
| 36679 | March 31 | Event | 1979 – The last British soldier leaves the Maltese Islands. Malta declares its Freedom Day (Jum il-Helsien). |
| 36680 | March 31 | Event | 1980 – The Chicago, Rock Island and Pacific Railroad operates its final train after being ordered to liquidate its assets because of bankruptcy and debts owed to creditors. |
| 36681 | March 31 | Event | 1985 – The first WrestleMania, the biggest wrestling event from the WWE (then the WWF), takes place in Madison Square Garden in New York. |
| 36682 | March 31 | Event | 1986 – Six metropolitan county councils are abolished in England. |
| 36683 | March 31 | Event | 1990 – Approximately 200,000 protestors take to the streets of London to protest against the newly introduced Poll Tax. |
| 36684 | March 31 | Event | 1991 – Georgian independence referendum, 1991: Nearly 99 percent of the voters support the country's independence from the Soviet Union. |
| 36685 | March 31 | Event | 1992 – The USS Missouri, the last active United States Navy battleship, is decommissioned in Long Beach, California. |
| 36686 | March 31 | Event | 1994 – The journal Nature reports the finding in Ethiopia of the first complete Australopithecus afarensis skull. |
| 36687 | March 31 | Event | 2004 – Iraq War in Anbar Province: In Fallujah, Iraq, four American private military contractors working for Blackwater USA, are killed after being ambushed. |
| 36688 | March 31 | Birth | 250 – Constantius Chlorus, Roman emperor (d. 306) |
| 36689 | March 31 | Birth | 1360 – Philippa of Lancaster (d. 1415) |
| 36690 | March 31 | Birth | 1425 – Bianca Maria Visconti, Italian wife of Francesco I Sforza (d. 1468) |