- May 3 Intercollegiate Athletic Association of the United States is renamed the National Collegiate Athletic Association (NCAA)
- May 4 Canadian Currency Act, 1910, receives Royal Assent
Event of Interest
May 4 Wilfrid Laurier passes the Naval Service Act, which creates the Royal Canadian Navy

Wilfrid Laurier
Nine Kings in One Room
May 6 George V becomes King of the United Kingdom upon the death of his father, Edward VII
Learn More- May 7 35th Preakness: R Estep aboard Layminster wins in 1:40.6
- May 10 1st aircraft air display held (Hendon, England)
- May 10 36th Kentucky Derby: Fred Herbert aboard Donau wins in 2:06.4
- May 10 Halley's Comet closest approach to Earth in 1910 pass
- May 10 The British House of Commons pass three major resolutions on political reform
- May 11 Montana's Glacier National Park forms

Lillian Wald
- May 12 Philadelphia Athletic's "Chief Bender" no-hits Cleveland Indians, 4-0
- May 14 Canada authorizes issuing of silver dollar coins
- May 15 The last time a major earthquake happened on the Elsinore Fault Zone
- May 16 US Bureau of Mines forms
- May 17 Canada sets the designs for the 1-50 cent coins
- May 19 Passage of Earth through tail of Halley's Comet causes near-panic
Event of Interest
May 20 Funeral for Britain's King Edward VII held in Westminster Abbey, has one of the largest assemblages of European royalty

Edward VII
- May 27 Reform of Prussian three-class voting system fails
- May 29 Pope's encyclical on Editae Saepe, against church reformers
- May 30 44th Belmont: James Butwell aboard Sweep wins in 2:22
- May 31 Cape of Good Hope becomes part of Union of South Africa
- May 31 Glenn Curtiss flies from Albany to NYC
- May 31 Union of South Africa declares its independence from the United Kingdom