| 82501 | July 21 | Event | 1949 – The United States Senate ratifies the North Atlantic Treaty. |
| 82502 | July 21 | Event | 1954 – First Indochina War: The Geneva Conference partitions Vietnam into North Vietnam and South Vietnam. |
| 82503 | July 21 | Event | 1959 – NS Savannah, the first nuclear-powered cargo-passenger ship, is launched as a showcase for Dwight D. Eisenhower's "Atoms for Peace" initiative. |
| 82504 | July 21 | Event | 1959 – Elijah Jerry "Pumpsie" Green becomes the first African-American to play for the Boston Red Sox, the last team to integrate. He came in as a pinch runner for Vic Wertz and stayed in as shortstop in a 2–1 loss to the Chicago White Sox. |
| 82505 | July 21 | Event | 1961 – Mercury program: Mercury-Redstone 4 Mission: Gus Grissom piloting Liberty Bell 7 becomes the second American to go into space (in a suborbital mission). |
| 82506 | July 21 | Event | 1970 – After 11 years of construction, the Aswan High Dam in Egypt is completed. |
| 82507 | July 21 | Event | 1972 – The Troubles: Bloody Friday: The Provisional IRA detonate 22 bombs in central Belfast, Northern Ireland, United Kingdom in the space of 80 minutes, killing nine and injuring 130. |
| 82508 | July 21 | Event | 1973 – In the Lillehammer affair in Norway, Israeli Mossad agents kill a waiter whom they mistakenly thought was involved in the 1972 Munich Olympics Massacre. |
| 82509 | July 21 | Event | 1976 – Christopher Ewart-Biggs, the British ambassador to the Republic of Ireland, is assassinated by the Provisional IRA. |
| 82510 | July 21 | Event | 1977 – The start of the four-day-long Libyan–Egyptian War. |
| 82511 | July 21 | Event | 1983 – The world's lowest temperature in an inhabited location is recorded at Vostok Station, Antarctica at −89.2 °C (−128.6 °F). |
| 82512 | July 21 | Event | 1995 – Third Taiwan Strait Crisis: The People's Liberation Army begins firing missiles into the waters north of Taiwan. |
| 82513 | July 21 | Event | 2001 – At the conclusion of a fireworks display on Okura Beach in Akashi, Hyōgo, Japan, 11 people are killed and more than 120 are injured when a pedestrian footbridge connecting the beach to JR Asagiri Station becomes overcrowded and people leaving the e |
| 82514 | July 21 | Event | 2008 – Ram Baran Yadav is declared the first president of Nepal. |
| 82515 | July 21 | Event | 2011 – NASA's Space Shuttle program ends with the landing of Space Shuttle Atlantis on mission STS-135. |
| 82516 | July 21 | Event | 2012 – Erden Eruç completes the first solo human-powered circumnavigation of the world. |
| 82517 | July 21 | Birth | 1620 – Jean Picard, French astronomer (d. 1682) |
| 82518 | July 21 | Birth | 1664 – Matthew Prior, English poet and diplomat, British Ambassador to France (d. 1721) |
| 82519 | July 21 | Birth | 1693 – Thomas Pelham-Holles, 1st Duke of Newcastle, English politician, Prime Minister of the United Kingdom (d. 1768) |
| 82520 | July 21 | Birth | 1710 – Paul Möhring, German physician, botanist, and zoologist (d. 1792) |
| 82521 | July 21 | Birth | 1783 – Charles Tristan, marquis de Montholon, French general (d. 1853) |
| 82522 | July 21 | Birth | 1808 – Simion Bărnuțiu, Romanian historian, academic, and politician (d. 1864) |
| 82523 | July 21 | Birth | 1810 – Henri Victor Regnault, French chemist and physicist (d. 1878) |
| 82524 | July 21 | Birth | 1816 – Paul Reuter, German-English journalist, founded Reuters (d. 1899) |
| 82525 | July 21 | Birth | 1851 – Sam Bass, American criminal (d. 1878) |
| 82526 | July 21 | Birth | 1858 – Maria Christina of Austria (d. 1929) |
| 82527 | July 21 | Birth | 1858 – Lovis Corinth, German painter (d. 1925) |
| 82528 | July 21 | Birth | 1858 – Alfred Henry O'Keeffe, New Zealand painter and educator (d. 1941) |
| 82529 | July 21 | Birth | 1863 – C. Aubrey Smith, English-American cricketer and actor (d. 1948) |
| 82530 | July 21 | Birth | 1870 – Emil Orlík, Czech painter, etcher, and lithographer (d. 1932) |