Wikipedia:Selected anniversaries/May 21
May 21: Armed Forces Day in the United States (2005), Navy Day in Chile
- 1674 - John Sobieski was elected by the szlachta to be King of the Polish-Lithuanian Commonwealth.
- 1881 - The American Red Cross was established by Clara Barton.
- 1894 - The Manchester Ship Canal was officially opened, linking the city of Manchester to the Irish Sea.
- 1927 - Aboard the Spirit of St. Louis, Charles Lindbergh completed the first solo non-stop transatlantic flight.
- 1991 - Former Indian prime minister Rajiv Gandhi was assassinated by a female suicide bomber.