September 18: Independence Day in Chile (1810)
- 96 - Nerva became Roman Emperor, ending the Flavian dynasty, and the era of the Five Good Emperors began.
- 1850 - The United States Congress passed the Fugitive Slave Act.
- 1851 - New York Times began publishing.
- 1895 - Daniel David Palmer made the first chiropractic adjustment.
- 1931 - The Mukden Incident: A section of a Japanese-built railroad was allegedly destroyed by Chinese terrorists, providing an excuse for the Japanese annexation of Manchuria.
Recent days: September 17 – September 16 – September 15