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1887 (MDCCCLXXXVII) was a common year starting on Saturday of the Gregorian calendar and a common year starting on Thursday of the Julian calendar, the 1887th year of the Common Era (CE) and Anno Domini (AD) designations, the 887th year of the 2nd millennium, the 87th year of the 19th century, and the 8th year of the 1880s decade. As of the start of 1887, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
- January 11 – Louis Pasteur's anti-rabies treatment is defended in the Académie Nationale de Médecine, by Dr. Joseph Grancher.
- January 20
- January 21
- The Amateur Athletic Union (AAU) is formed in the United States.
- Brisbane receives a one-day rainfall of 465 millimetres (18.3 in) (a record for any Australian capital city).
- January 24 – Battle of Dogali: Abyssinian troops defeat the Italians.
- January 28
- In a snowstorm at Fort Keogh, Montana, the largest snowflakes on record are reported. They are 15 inches (38 cm) wide and 8 inches (20 cm) thick.
- Construction work begins on the foundations of the Eiffel Tower in Paris, France.
- February 2 – The first Groundhog Day is observed in Punxsutawney, Pennsylvania.
- February 4 – The Interstate Commerce Act of 1887, passed by the 49th United States Congress, is signed into law by President Grover Cleveland.
- February 5 – The Giuseppe Verdi opera Otello premieres at La Scala, Milan.
- February 8 – The Dawes Act, or the General Allotment Act, is enacted in the United States.
- February 23 – The French Riviera is hit by a large earthquake, killing around 2,000 along the coast of the Mediterranean.
- February 26 – At the Sydney Cricket Ground, George Lohmann becomes the first bowler to take eight wickets, in a Test innings.
- March 3 – Anne Sullivan begins teaching Helen Keller.
- March 7 – North Carolina State University is established, as North Carolina College of Agriculture and Mechanic Arts.
- March 13 – Chester Greenwood patents earmuffs in the United States.
- April 1 – The final of the first All-Ireland Hurling Championship is held.
- April 4 – Argonia, Kansas, elects Susanna M. Salter as the first female mayor in the United States.
- April 10 (Easter Sunday) – The Catholic University of America is founded in Washington, D.C.
- April 20 – Occidental College is founded in Los Angeles, California.
- April 21 – Schnaebele incident: A French/German border incident nearly leads to war between the two countries.
- May 3 – An earthquake hits Sonora, Mexico.
- May 9 – Buffalo Bill's Wild West Show opens in London.
- May 14 – The cornerstone of the new Stanford University, in northern California, is laid (the college opens in 1891).
- May 25 – The Hells Canyon massacre begins: 34 Chinese gold miners are ambushed and murdered in Hells Canyon, Oregon, United States.
- June 8 – Herman Hollerith receives a U.S. patent for his punched card calculator.
- June 18 – The Reinsurance Treaty is closed between Germany and Russia.
- June 21
- June 23 – The Rocky Mountains Park Act becomes law in Canada, creating that nation's first national park, Banff National Park.
- July – James Blyth operates the first working wind turbine at Marykirk, Scotland.
- July 1 – Construction of the iron structure of the Eiffel Tower starts in Paris, France.
- July 6 – King Kalākaua of Hawai'i is forced by anti-monarchists to sign the 'Bayonet Constitution', stripping the Hawaiian monarchy of much of its authority, as well as disenfranchising most native Hawaiians, all Asians and the poor.
- July 12 – Odense Boldklub, the Danish football team, is founded as the Odense Cricket Club.
- July 19 – Dorr Eugene Felt receives the first U.S. patent for his comptometer.
- July 26
- August – The earliest constituent of the U.S. National Institutes of Health is established at the Marine Hospital, Staten Island, as the Laboratory of Hygiene.
- August 8 – Antonio Guzmán Blanco ends his term as President of Venezuela.
- August 13 – Hibernian F.C. of Scotland defeats Preston North End F.C. of England to win the 'Championship of the World', after the two teams win the Association football Cup competitions in their respective countries.
- September 5 – The Theatre Royal, Exeter, England, burns down, killing 186 people.
- September 28 – The 1887 Yellow River flood begins in China, killing 900,000 to 2,000,000 people.
- October 1 – The British Empire takes over Balochistan.
- October 3 – Florida A&M University opens its doors in Tallahassee, Florida.
- October 12 – Yamaha Corporation, the global musical instrument and audiovisual brand, is founded as Yamaha Organ Manufacturing in Hamamatsu, Japan.
- November 3 – The Coimbra Academic Association, the students' union of the University of Coimbra in Portugal, is founded.
- November 6 – The Association football club Celtic F.C. is formed in Glasgow, Scotland, by Irish Marist Brother Walfrid, to help alleviate poverty in the city's East End by raising money for his charity, the 'Poor Children's Dinner Table'.
- November 8 – Emile Berliner is granted a U.S. patent for the Berliner Gramophone.
- November 10 – Louis Lingg, sentenced to be hanged for his alleged role in the Haymarket affair (a bombing in Chicago on May 4, 1886), kills himself by dynamite.
- November 11 – August Spies, Albert Parsons, Adolph Fischer and George Engel are hanged for inciting riot and murder in the Haymarket affair.
- November 13 – Bloody Sunday: Police in London clash with radical and Irish nationalist protesters.
- December 5 – The International Bureau of Intellectual Property is established.
- December 25 – Glenfiddich single malt Scotch whisky is first produced.
- Laos and Cambodia are added to French Indochina.
- Heinrich Hertz discovers the photoelectric effect on the production and reception of electromagnetic (EM) waves (radio); this is an important step towards the understanding of the quantum nature of light.
- Franz König publishes "Über freie Körper in den Gelenken" in the medical journal Deutsche Zeitschrift für Chirurgie, describing (and naming) the disease Osteochondritis dissecans for the first time.
- Teachers College, later part of Columbia University, is founded.
- The first English-language edition of Friedrich Engels' 1844 study of The Condition of the Working Class in England, translated by Florence Kelley, is published in New York City.
- Publication in Barcelona of Enrique Gaspar's El anacronópete, the first work of fiction to feature a time machine.
- Publication begins of Futabatei Shimei's The Drifting Cloud (Ukigumo), the first modern novel in Japan.
- The Hermetic Order of the Golden Dawn is founded.
- Nagase Shoten (長瀬商店), predecessor of Japanese cosmetics and toiletry brand Kao Corporation, is founded in Nihonbashi, Tokyo, Japan.
- Tokyo Fire Insurance, predecessor of Sompo Japan Nipponkoa Insurance, is founded.
- Global construction and real estate development company Skanska is founded in Malmö, Sweden.
- American financial services company A. G. Edwards is founded by General Albert Gallatin Edwards in St. Louis, Missouri.
- Heyl & Patterson Inc., a pioneer in coal unloading equipment, is founded by Edmund W. Heyl and William J. Patterson in Pittsburgh, Pennsylvania.
- The first battery rail car is used on the Royal Bavarian State Railways.