Wikipedia:Selected anniversaries/March 31
- 1854 - Commodore Matthew Perry of the U.S. Navy signed the Treaty of Kanagawa, forcing the opening of Japanese ports to American trade.
- 1889 - The Eiffel Tower was inaugurated in Paris.
- 1903 - New Zealander inventor Richard Pearse reportedly flew in one of the first flying machines.
- 1917 - The Danish West Indies became the U.S. Virgin Islands after the United States paid Denmark US$25 million for the Caribbean islands.
- 1930 - Hollywood movie studios instituted the Production Code to avoid government censorship.