June 21: Summer solstice in the Northern Hemisphere and Winter solstice in the Southern Hemisphere (12:26 UTC), Midsummer in northern Europe
- 1734 - A black slave known as Marie-Joseph Angélique, after having been convicted of setting the fire that destroyed much of the city of Montreal, was tortured and then hanged in New France.
- 1788 - New Hampshire ratified the U.S. Constitution and was admitted as the 9th U.S. state.
- 1813 - Laura Secord set out to warn British forces of an impending American attack at Queenston, Ontario.
- 1864 - New Zealand land wars: The Tauranga Campaign ended.
- 1985 - Greenland officially adopted its own flag (pictured), adding support to its independence movement.
- 2000 - The controversial amendment known as Section 28 was repealed in Scotland with a 99 to 17 vote.