1787Centuries: 17th century - 18th century - 19th century
- In Britain, Thomas Clarkson and Granville Sharp formed the "Society for the Abolition of the Slave Trade" with support from John Wesley, Josiah Wedgwood and others.
- January 11 - William Herschel discovers Titania and Oberon, two moonss of Uranus.
- February 4 - Shays' Rebellion fails
- May 13 - Captain Arthur Phillip leaves Portsmouth, England with eleven ships full of convicts to establish a penal colony in Australia.
- May 14 - In Philadelphia, Pennsylvania, delegates begin to meet to write a new Constitution for the United States.
- May 25 - In Philadelphia, Pennsylvania, delegates begin to convene a Constitutional Convention to write a new Constitution for the United States (George Washington is presiding).
- July 13 - The United States Congress enacts the Northwest Ordinance establishing governing rules for the Northwest Territory. It also establishes procedures for the admission of new states and limits the expansion of slavery.
- September 17 - United States Constitution adopted
- December 7 - Delaware ratifies the Constitution and becomes the first U.S. state.
- December 12 - Pennsylvania becomes the second U.S. state.
- December 18 - New Jersey becomes the third U.S. state.
- June 20 - Karl Friedrich Abel, aged 63, German baroque composer
- November 3 - Robert Lowth, Bishop of the Church of England
- November 15 - Christoph Willibald Gluck, composer