Wikipedia:Selected anniversaries/July 3
On July 3:
- 323 - Constantine the Great defeated Licinius
- 1608 - Quebec City was founded by Samuel de Champlain
- 1938 - World record for a steam railway locomotive: the "Mallard", which reached a speed of 203 km/h (126 mph)
- 1964 - President Lyndon Johnson of the United States signed the Civil Rights Act of 1964, which prohibits racial segregation in public places