May 1, 1006
- Supernova SN 1006, the brightest supernova in recorded history, appears in the constellation Lupus.
May 1, 1776
- Establishment of the Illuminati in Ingolstadt (Upper Bavaria), by Jesuit-taught Adam Weishaupt.
May 1, 1901
- The Pan-American Exposition opens in Buffalo, New York.
May 2, 1866
- Peruvian defenders fight off Spanish fleet at the Battle of Callao.
May 2, 1885
- Good Housekeeping
magazine goes on sale for the first time.
May 2, 1969
- The British ocean liner Queen Elizabeth 2
departs on her maiden voyage to New York City.
May 3, 1481
- The largest of three earthquakes strikes the island of Rhodes and causes an estimated 30,000 casualties.
May 3, 1877
- Labatt Park, the oldest continually operating baseball grounds in the world has its first game.
May 3, 1901
- The Great Fire of 1901 begins in Jacksonville, Florida.
May 5, 1891
- The Music Hall in New York City (later known as Carnegie Hall) has its grand opening and first public performance, with Tchaikovsky as the guest conductor.
May 6, 1937
- The German zeppelin Hindenburg
catches fire and is destroyed within a minute while attempting to dock at Lakehurst, New Jersey. Thirty-six people are killed.
May 7, 1824
- World premiere of Ludwig van Beethoven's Ninth Symphony in Vienna, Austria.
May 8, 1886
- Pharmacist John Styth Pemberton first sells a carbonated beverage named "Coca-Cola" as a patent medicine.
May 9, 1877
- A magnitude 8.8 earthquake off the coast of Peru kills 2,541, including some as far away as Hawaii and Japan.
May 10, 1503
- Christopher Columbus visits the Cayman Islands and names them Las Tortugas after the numerous turtles there.
May 11, 1858
- Minnesota is admitted as the 32nd U.S. State.
May 12, 1863
- Two divisions of James B. McPherson's XVII Corps (ACW) turn the left wing of Confederate General John C. Pemberton's defensive line on Fourteen Mile Creek, opening up the interior of Mississippi to the Union Army during the Vicksburg Campaign.
May 15, 1940
- McDonald's opens its first restaurant in San Bernardino, California.
May 17, 1849
- A large fire nearly burns St. Louis, Missouri to the ground.
May 18, 1910
- The Earth passes through the tail of Comet Halley.
May 19, 1780
- A combination of thick smoke and heavy cloud cover causes complete darkness to fall on Eastern Canada and the New England area of the United States at 10:30 A.M.
May 20, 1873
- Levi Strauss and Jacob Davis receive a U.S. patent for blue jeans with copper rivets.
May 22, 1960
- An earthquake measuring 9.5 on the moment magnitude scale, now known as the Great Chilean Earthquake, hits southern Chile.
May 23, 1829
- Accordion patent granted to Cyrill Demian in Vienna.
May 25, 1935
- Jesse Owens of Ohio State University breaks three world records and ties a fourth at the Big Ten Conference Track and Field Championships in Ann Arbor, Michigan.
May 26, 451
- Battle of Avarayr between Armenian rebels and the Sassanid Empire takes place.
May 27, 1798
- The Battle of Oulart Hill takes place in Wexford, Ireland.
May 28, 1930
- The Chrysler Building in New York City officially opens.
May 29, 1848
- Wisconsin is admitted as the 30th U.S. state.
May 30, 1971
- Mariner 9
is launched to map 70% of the surface, and to study temporal changes in the atmosphere and surface, of Mars.
May 31, 1889
- Over 2,200 people die after a dam break sends a 60-foot (18-meter) wall of water over the town of Johnstown, Pennsylvania.