- 21 May, 1844 – After seeing the samples produced by Charles Goodyear, Thomas Hancock becomes the first person to patent vulcanization of rubber
- 16 May, 1919 – A naval Curtiss aircraft NC-4 commanded by Albert Cushing Read leaves Trepassey, Newfoundland, for Lisbon via the Azores on the first transatlantic flight
- 28 May, 1937 – German automobile manufacturer Volkswagen is founded
- 3 May, 2000 – The outdoor recreation activity Geocaching (logo pictured), in which players use GPS to find hidden containers, is first played