March 9 is the 69th day of the year. There are 297 days remaining until the end of the year.
- 1841 – The United States Supreme Court ruled that captive Africans who had seized control of the ship carrying them had been taken into slavery illegally.
- 1842 – The first documented discovery of gold in California occurred at Rancho San Francisco, six years before the California Gold Rush.
- 1933 – President Franklin D. Roosevelt submitted the Emergency Banking Act to Congress, the first of his New Deal policies.
- 1959 – The Barbie doll made its debut at the American International Toy Fair in New York.
- 1990 – Dr. Antonia Novello was sworn in as the first woman and Hispanic American US Surgeon General.
- 2010 – The first same-sex marriages in Washington, D.C. took place.
- 2011 – Space Shuttle Discovery makes its final landing after 39 flights.