| 74461 | June 30 | Event | 1860 – The 1860 Oxford evolution debate at the Oxford University Museum of Natural History takes place. |
| 74462 | June 30 | Event | 1859 – French acrobat Charles Blondin crosses Niagara Falls on a tightrope. |
| 74463 | June 30 | Event | 1864 – U.S. President Abraham Lincoln grants Yosemite Valley to California for "public use, resort and recreation". |
| 74464 | June 30 | Event | 1882 – Charles J. Guiteau is hanged in Washington, D.C. for the assassination of U.S. President James Garfield. |
| 74465 | June 30 | Event | 1886 – The first transcontinental train trip across Canada departs from Montreal. It arrives in Port Moody, British Columbia on July 4. |
| 74466 | June 30 | Event | 1892 – The Homestead Strike begins near Pittsburgh, Pennsylvania. |
| 74467 | June 30 | Event | 1905 – Albert Einstein sends the article On the Electrodynamics of Moving Bodies, in which he introduces special relativity, for publication in Annalen der Physik. |
| 74468 | June 30 | Event | 1906 – The United States Congress passes the Meat Inspection Act and Pure Food and Drug Act. |
| 74469 | June 30 | Event | 1908 – The Tunguska event occurs in remote Siberia. |
| 74470 | June 30 | Event | 1912 – The Regina Cyclone hits Regina, Saskatchewan, killing 28. It remains Canada's deadliest tornado event. |
| 74471 | June 30 | Event | 1917 – World War I: Greece declares war on the Central Powers. |
| 74472 | June 30 | Event | 1921 – U.S. President Warren G. Harding appoints former President William Howard Taft Chief Justice of the United States. |
| 74473 | June 30 | Event | 1922 – In Washington D.C., U.S. Secretary of State Charles Evans Hughes and Dominican Ambassador Francisco J. Peynado sign the Hughes–Peynado agreement, which ends the United States occupation of the Dominican Republic. |
| 74474 | June 30 | Event | 1934 – The Night of the Long Knives, Adolf Hitler's violent purge of his political rivals in Germany, takes place. |
| 74475 | June 30 | Event | 1936 – Emperor Haile Selassie of Abyssinia appeals for aid to the League of Nations against Italy's invasion of his country. |
| 74476 | June 30 | Event | 1937 – The world's first emergency telephone number, 999, is introduced in London |
| 74477 | June 30 | Event | 1944 – World War II: The Battle of Cherbourg ends with the fall of the strategically valuable port to American forces. |
| 74478 | June 30 | Event | 1953 – The first Chevrolet Corvette rolls off the assembly line in Flint, Michigan. |
| 74479 | June 30 | Event | 1956 – A TWA Super Constellation and a United Airlines DC-7 collide above the Grand Canyon in Arizona and crash, killing all 128 on board both airliners. |
| 74480 | June 30 | Event | 1959 – A United States Air Force F-100 Super Sabre from Kadena Air Base, Okinawa, crashes into a nearby elementary school, killing 11 students plus six residents from the local neighborhood. |
| 74481 | June 30 | Event | 1960 – Congo gains independence from Belgium. |
| 74482 | June 30 | Event | 1963 – Ciaculli massacre: a car bomb, intended for Mafia boss Salvatore Greco, kills seven police officers and military personnel near Palermo. |
| 74483 | June 30 | Event | 1966 – The National Organization for Women, the United States' largest feminist organization, is founded. |
| 74484 | June 30 | Event | 1968 – Pope Paul VI issues the Credo of the People of God. |
| 74485 | June 30 | Event | 1971 – The crew of the Soviet Soyuz 11 spacecraft are killed when their air supply escapes through a faulty valve. |
| 74486 | June 30 | Event | 1971 – Ohio ratifies the 26th Amendment to the U.S. Constitution, reducing the voting age to 18, thereby putting the amendment into effect. |
| 74487 | June 30 | Event | 1972 – The first leap second is added to the UTC time system. |
| 74488 | June 30 | Event | 1974 – The Baltimore municipal strike of 1974 begins. |
| 74489 | June 30 | Event | 1977 – The Southeast Asia Treaty Organization disbands. |
| 74490 | June 30 | Event | 1985 – Thirty-nine American hostages from the hijacked TWA Flight 847 are freed in Beirut after being held for 17 days. |