| | 786 - Harun al-Rashid becomes the Abbasid caliph upon the death of his brother al-Hadi. |
| | 1752 - The British Empire adopts the Gregorian calendar, skipping eleven days (the previous day was September 2). |
| | 1812 - French grenadiers enter Moscow. |
| | 1814 - Francis Scott Key writes The Star-Spangled Banner. |
| | 1829 - Ottoman Empire signs the Treaty of Adrianople with Russia, thus ending the Russo-Turkish War |
| | 1847 - Mexican-American War: Winfield Scott captures Mexico City. |
| | 1886 - Typewriter ribbon patented. |
| | 1901 - President of the United States William McKinley dies after an assassination attempt on September 6, and is succeeded by Theodore Roosevelt. |
| | 1917 - Republican government declared in Russia. |
| | 1923 - Miguel Primo de Rivera becomes dictator of Spain. |
| | 1944 - United States Marines land on the island of Peleliu. |
| | 1948 - Groundbreaking for the United Nations headquarters in New York City. |
| | 1958 - Two rockets designed by the German engineer Ernst Mohr, the first German post-war rockets, reach the upper atmosphere. |
| | 1959 - The Soviet probe Luna 2 crashes onto the Moon, becoming the first man-made object to reach it. |
| | 1960 - The Organization of the Petroleum Exporting Countries (OPEC) is founded. |
| | 1964 - The opening of the third period of the Second Vatican Council. |
| | 1965 - The opening of the fourth and final period of Second Vatican Council. |
| | 1975 - The first American saint, Elizabeth Ann Seton, is canonized by Pope Paul VI. |
| | 1984 - Joe Kittinger becomes the first person to fly a hot air balloon alone across the Atlantic Ocean. |
| | 1987 - ITV Schools was broadcast on Channel 4 for the very first time. |
| | 1990 - Ken Griffey, Jr. and his father, Ken Griffey, Sr. become the first father-son duo to hit back-to-back home runs. |
| | 1994 - The Major League Baseball season is canceled due to strike. |
| | 1998 - Telecommunications companies MCI Communications and WorldCom complete their $37 billion merger to form MCI WorldCom. |
| | 1999 - Kiribati, Nauru and Tonga join the United Nations. |
| | 2001 - Historic National Prayer Service held at Washington National Cathedral for victims of the September 11 attacks. A similar service is held in Canada on Parliament Hill, the largest vigil ever held in the nation's capital. |
| | 2003 - In a referendum Sweden rejects adopting the euro. |
| | 2003 - Estonia approves joining the European Union in a referendum. |