- May 7 Paraguayian government unleashes contra revolt
Sports History
May 8 A movement among Card players to protest its 1st meeting with Jackie Robinson & the Dodgers is aborted by a talk from owner Sam Breadon
Historic Event
May 8 Polish resistance fighter Witold Pilecki, who had volunteered to be imprisoned in Auschwitz to gain information about the Holocaust, is arrested by Polish communist police
- May 10 "Chocolate Soldier" closes at Century Theater NYC after 69 performances
- May 10 72nd Preakness: Doug Dodson aboard Faultless wins in 1:59
- May 11 BF Goodrich announced the development of tubeless tire (Akron Ohio)
- May 11 Laos accepts constitution for parliamentary democracy
- May 13 US Senate approves the Taft-Hartley Act limiting the power of unions
Music History
May 16 Billie Holiday is arrested in her New York apartment for possession of narcotics
- May 17 "Street Scene" closes at Adelphi Theater NYC after 148 performances
- May 18 MLB Philadelphia A's catcher Warren Rosar catches his 147th game without an error
- May 22 "Truman Doctrine" goes into effect, aiding Turkey and Greece
- May 22 1st US ballistic missile fired
- May 23 PC Hooft prize forms for literature
- May 25 Coal dust explosion rocks Centralia Coal Co's Mine #5 killing 111 in Illinois
- May 30 Indianapolis 500: Mauri Rose leads for final 8 laps after confused pit messages with teammate Bill Holland to take the controversial victory; race marred by a 41st lap crash that claims life of Shorty Cantlon
- May 31 79th Belmont: Ruperto Donoso aboard Phalanx wins in 2:29.6
- May 31 Communists seize power in Hungary
- May 31 Eastern DC-4 crashes between Ft Deposit & Perryville Md, kills 53
- May 31 Italian government of Gasperi forms