| 110521 | September 27 | Event | 1777 – Lancaster, Pennsylvania is the capital of the United States, for one day. |
| 110522 | September 27 | Event | 1821 – Mexico gains its independence from Spain. |
| 110523 | September 27 | Event | 1822 – Jean-François Champollion announces that he has deciphered the Rosetta Stone. |
| 110524 | September 27 | Event | 1825 – The world's first public railway to use steam locomotives, the Stockton and Darlington Railway, is ceremonially opened. |
| 110525 | September 27 | Event | 1854 – The steamship SS Arctic sinks with 300 people on board. This marks the first great disaster in the Atlantic Ocean. |
| 110526 | September 27 | Event | 1875 – The merchant sailing ship Ellen Southard is wrecked in a storm at Liverpool the United States Congress subsequently awards 27 gold Lifesaving Medals to the lifeboat men who went to rescue her crew. |
| 110527 | September 27 | Event | 1903 – Wreck of the Old 97, a train crash made famous by the song of the same name. |
| 110528 | September 27 | Event | 1905 – The physics journal Annalen der Physik received Albert Einstein's paper "Does the Inertia of a Body Depend Upon Its Energy Content?", introducing the equation E=mc². |
| 110529 | September 27 | Event | 1908 – The first production of the Ford Model T automobile was built at the Piquette Plant in Detroit. |
| 110530 | September 27 | Event | 1916 – Iyasu V is proclaimed deposed as ruler of Ethiopia in a palace coup in favor of his aunt Zewditu. |
| 110531 | September 27 | Event | 1922 – King Constantine I of Greece abdicates his throne in favor of his eldest son, George II. |
| 110532 | September 27 | Event | 1928 – The Republic of China is recognized by the United States. |
| 110533 | September 27 | Event | 1930 – Bobby Jones wins the U.S. Amateur Championship to complete the Grand Slam of golf. The old structure of the grand slam was the U.S. Open, British Open, U.S. Amateur, and British Amateur. |
| 110534 | September 27 | Event | 1937 – Bali tiger declared extinct. |
| 110535 | September 27 | Event | 1938 – Ocean liner Queen Elizabeth launched in Glasgow. |
| 110536 | September 27 | Event | 1940 – World War II: The Tripartite Pact is signed in Berlin by Germany, Japan and Italy. |
| 110537 | September 27 | Event | 1941 – The SS Patrick Henry is launched becoming the first of more than 2,700 Liberty ships. |
| 110538 | September 27 | Event | 1942 – Last day of the September Matanikau action on Guadalcanal as United States Marine Corps troops barely escape after being surrounded by Japanese forces near the Matanikau River. |
| 110539 | September 27 | Event | 1944 – The Kassel Mission results in the largest loss by a USAAF group on any mission in World War II. |
| 110540 | September 27 | Event | 1949 – The first Plenary Session of the National People's Congress approves the design of the Flag of the People's Republic of China. |
| 110541 | September 27 | Event | 1954 – The nationwide debut of Tonight Starring Steve Allen (The Tonight Show) hosted by Steve Allen on NBC. |
| 110542 | September 27 | Event | 1956 – USAF Captain Milburn G. Apt becomes the first man to exceed Mach 3 while flying the Bell X-2. Shortly thereafter, the craft goes out of control and Captain Apt is killed. |
| 110543 | September 27 | Event | 1959 – Nearly 5,000 people die on the main Japanese island of Honshū as the result of a typhoon. |
| 110544 | September 27 | Event | 1961 – Sierra Leone joins the United Nations. |
| 110545 | September 27 | Event | 1962 – The Yemen Arab Republic is established. |
| 110546 | September 27 | Event | 1964 – The British TSR-2 aircraft XR219 makes its maiden flight from Boscombe Down in Wiltshire. |
| 110547 | September 27 | Event | 1968 – The stage musical Hair opens at the Shaftesbury Theatre in London, where it played 1,998 performances until its closure was forced by the roof collapsing in July 1973. |
| 110548 | September 27 | Event | 1975 – The last use of capital punishment in Spain sees the executions of five members of militant organisations, sparking worldwide protests against the Spanish government and the withdrawal of numerous ambassadors. |
| 110549 | September 27 | Event | 1977 – A U.S. Navy McDonnell Douglas F-4 Phantom II crashes into a residential neighborhood in Yokohama, Japan, killing two children on the ground and injuring seven other people. |
| 110550 | September 27 | Event | 1979 – The United States Department of Education receives final approval from the U.S. Congress to become the 13th US Cabinet agency. |