Births on April 23

Simone Simon, French actress (d. 2005)

Simone Thérèse Fernande Simon (23 April 1910 or 1911 – 22 February 2005) was a French film actress who began her film career in 1931.

11 May

Glacier National Park (U.S.)
An act of the U.S. Congress establishes Glacier National Park in Montana.
4 Jul

Jack Johnson (boxer)
African-American boxer Jack Johnson knocks out white boxer Jim Jeffries in a heavyweight boxing match, sparking race riots across the United States.
15 Jul

Alzheimer's disease
In his book Clinical Psychiatry, Emil Kraepelin gives a name to Alzheimer's disease, naming it after his colleague Alois Alzheimer.
18 Sep

Suffrage
In Amsterdam, 25,000 demonstrate for general suffrage.
7 Nov

Wright brothers
The first air freight shipment (from Dayton, Ohio, to Columbus, Ohio) is undertaken by the Wright brothers and department store owner Max Moorehouse.