Royal Canadian Navy Established
May 4 Wilfrid Laurier passes the Naval Service Act, which creates the Royal Canadian Navy
- 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
- May 12 Philadelphia Athletics pitcher Charles "Chief" Bender no-hits Cleveland Naps, 4-0
Second NAACP Conference
May 12 Second NAACP conference in NYC
Meeting of Interest
May 20 Funeral for Britain's King Edward VII held in Westminster Abbey, has one of the largest assemblages of European royalty
Louis Botha Prime Minister
May 21 Louis Botha becomes the first Prime Minister of the Union of South Africa
- May 27 Reform of Prussian three-class voting system fails
- May 29 Pope Pius X'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