- May 1 Charlie Robertson of Chicago pitches a perfect no-hit, no-run game
- May 2 WBAP-AM begins broadcasting from Fort Worth, Texas
- May 3 Mayor Hylan closes streets for building of Yankee Stadium
- May 3 Salt layer find at Winterswijk
- May 4 KNX-AM in Los Angeles CA begins radio transmissions
- May 5 Construction begins on Yankee Stadium (Bronx)
- May 7 Belgian soccer team defeats Netherlands: 1-2
- May 7 NY Giant Jesse Barnes no-hits Phillies, 2-0
Event of Interest
May 9 The International Astronomical Union formally adopt Annie Jump Cannon's stellar classification system, which with only minor changes, is still used today
Annie Jump Cannon
- May 10 Dr Ivy Williams is 1st woman to be called to the English Bar
- May 10 WHB-AM in Kansas City MO begins radio transmissions
- May 10 The United States annexes the Kingman Reef in n the North Pacific Ocean
- May 13 48th Kentucky Derby: Albert Johnson aboard Morvich wins in 2:04.6
- May 13 47th Preakness: L Morris aboard Pillory wins in 1:51.6
- May 15 Germany turns over the Upper Silesia region to Poland under Allied pressure and despite a plebiscite in favor of merging with Germany
- May 16 White Star Liner Majestic completes 5½ day maiden voyage
- May 18 Dutch 2nd Chamber agrees to 48 hour work week (was 45 hrs)
- May 20 "Egypt" sinks off Ushant after colliding with "Seine" killing 90
Event of Interest
May 20 Babe Ruth and Bob Meusel, previously suspended by Judge Kenesaw Mountain Landis, return to the NY lineup and go hitless
Babe Ruth
Kenesaw Mountain Landis
Event of Interest
May 21 Pulitzer prize awarded to Eugene O'Neill for his play "Anna Christie"
Eugene O'Neill
- May 21 Ruppert buys out Huston interest in Yankees for $15 million
- May 23 "Abie's Irish Rose" 1st of over 2,500 performances
- May 23 Future World Heavyweight boxing champion Gene Tunney suffers his only professional defeat in 15-round unanimous points decision against Harry Greb at Madison Square Garden, NY
Event of Interest
May 23 Walt Disney incorporates his 1st film company Laugh-O-Gram Films
Walt Disney
Event of Interest
May 26 Vladimir Lenin suffers a stroke
Vladimir Lenin
Event of Interest
May 30 Completed Lincoln Memorial dedicated by US Chief Justice William H. Taft in front of 50,000
Henry Bacon