- May 1 US Quarantine Station opens on Angel Island, San Francisco Bay
- May 11 18th Kentucky Derby: Lonnie Clayton aboard Azra wins in 2:41½
- May 14 Vitesse 1892 soccer team forms in Arnhem
- May 19 Charles Brady King invents pneumatic hammer
- May 19 National Society of Colonial Dames of America founded
- May 20 George Sampson patents clothes dryer
- May 21 Ruggero Leoncavallo's opera "I Pagliacci" premieres in Milan
- May 22 Dr Washington Sheffield invents the toothpaste tube
