| 38119 | April 3 | Event | 1969 – Vietnam War: United States Secretary of Defense Melvin Laird announces that the United States will start to "Vietnamize" the war effort. |
| 38120 | April 3 | Event | 1973 – Martin Cooper of Motorola makes the first handheld mobile phone call to Joel S. Engel of Bell Labs, though it took ten years for the DynaTAC 8000X to become the first such phone to be commercially released. |
| 38121 | April 3 | Event | 1974 – The 1974 Super Outbreak occurs, the second biggest tornado outbreak in recorded history (after the 2011 Super Outbreak). The death toll is 315, with nearly 5,500 injured. |
| 38122 | April 3 | Event | 1975 – Bobby Fischer refuses to play in a chess match against Anatoly Karpov, giving Karpov the title of World Champion by default. |
| 38123 | April 3 | Event | 1981 – The Osborne 1, the first successful portable computer, is unveiled at the West Coast Computer Faire in San Francisco. |
| 38124 | April 3 | Event | 1996 – Suspected "Unabomber" Theodore Kaczynski is captured at his cabin in Montana, United States. |
| 38125 | April 3 | Event | 1996 – A United States Air Force airplane carrying United States Secretary of Commerce Ron Brown crashes in Croatia, killing all 35 on board. |
| 38126 | April 3 | Event | 1997 – The Thalit massacre begins in Algeria all but one of the 53 inhabitants of Thalit are killed by guerrillas. |
| 38127 | April 3 | Event | 2000 – United States v. Microsoft Corp.: Microsoft is ruled to have violated United States antitrust law by keeping "an oppressive thumb" on its competitors. |
| 38128 | April 3 | Event | 2004 – Islamic terrorists involved in the 2004 Madrid train bombings are trapped by the police in their apartment and kill themselves. |
| 38129 | April 3 | Event | 2007 – Conventional-Train World Speed Record: A French TGV train on the LGV Est high speed line sets an official new world speed record. |
| 38130 | April 3 | Event | 2008 – ATA Airlines, once one of the ten largest U.S. passenger airlines and largest charter airline, files for bankruptcy for the second time in five years and ceases all operations. |
| 38101 | April 3 | Event | 1860 – The first successful United States Pony Express run from St. Joseph, Missouri, to Sacramento, California, begins. |
| 38102 | April 3 | Event | 1865 – American Civil War: Union forces capture Richmond, Virginia, the capital of the Confederate States of America. |
| 38103 | April 3 | Event | 1882 – American Old West: Jesse James is killed by Robert Ford. |
| 38104 | April 3 | Event | 1885 – Gottlieb Daimler is granted a German patent for his engine design. |
| 38105 | April 3 | Event | 1888 – The first of eleven unsolved brutal murders of women committed in or near the impoverished Whitechapel district in the East End of London, occurs. |
| 38106 | April 3 | Event | 1895 – The trial in the libel case brought by Oscar Wilde begins, eventually resulting in his imprisonment on charges of homosexuality. |
| 38107 | April 3 | Event | 1922 – Joseph Stalin becomes the first General Secretary of the Communist Party of the Soviet Union. |
| 38108 | April 3 | Event | 1929 – RMS Queen Mary is ordered from John Brown & Company Shipbuilding and Engineering by Cunard Line. |
| 38109 | April 3 | Event | 1933 – First flight over Mount Everest, a British expedition, led by the Marquis of Clydesdale, and funded by Lucy, Lady Houston. |
| 38110 | April 3 | Event | 1936 – Bruno Richard Hauptmann is executed for the kidnapping and death of Charles Augustus Lindbergh, Jr., the baby son of pilot Charles Lindbergh. |
| 38111 | April 3 | Event | 1942 – World War II: Japanese forces begin an assault on the United States and Filipino troops on the Bataan Peninsula. |
| 38112 | April 3 | Event | 1946 – Japanese Lt. General Masaharu Homma is executed in the Philippines for leading the Bataan Death March. |
| 38113 | April 3 | Event | 1948 – United States President Harry S. Truman signs the Marshall Plan, authorizing $5 billion in aid for 16 countries. |
| 38114 | April 3 | Event | 1948 – In Jeju Province, South Korea, a civil-war-like period of violence and human rights abuses begins, known as the Jeju massacre. |
| 38115 | April 3 | Event | 1955 – The American Civil Liberties Union announces it will defend Allen Ginsberg's book Howl against obscenity charges. |
| 38116 | April 3 | Event | 1956 – Hudsonville–Standale tornado: The western half of the Lower Peninsula of Michigan is struck by a deadly F5 tornado. |
| 38117 | April 3 | Event | 1961 – The Leadbeater's possum is rediscovered in Australia after 72 years. |
| 38118 | April 3 | Event | 1968 – Martin Luther King Jr. delivers his "I've Been to the Mountaintop" speech. |