- 1707 Acts of Union comes into force, uniting England and Scotland to form the United Kingdom of Great Britain
- 1753 Publication of Species Plantarum by Linnaeus, and the formal start date of plant taxonomy adopted by the International Code of Botanical Nomenclature.
- 1841 First emigrant wagon train leaves Independence, Missouri, for California
- 1886 US general strike for 8-hour working day begins
- 1898 US Admiral George Dewey commands "You may fire when you are ready, Gridley" as US route Spanish fleet at Manila
- 1931 Empire State Building opens in New York City
"Penny Blacks", first adhesive postage stamps issued by Great Britain
On May 1, 1840