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1880 (MDCCCLXXX)was a leap year starting on Thursday of the Gregorian calendar and a leap year starting on Tuesday of the Julian calendar, the 1880th year of the Common Era (CE) and Anno Domini (AD) designations, the 880th year of the 2nd millennium, the 80th year of the 19th century, and the 1st year of the 1880s decade. As of the start of 1880, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
- January 22 – Toowong State School is founded in Queensland, Australia.
- February – The journal Science is first published in the United States, with financial backing from Thomas Edison.
- February 2
- The first electric streetlight is installed in Wabash, Indiana.
- The first successful shipment of frozen mutton from Australia arrives in London, aboard the SS Strathleven.
- February 4 – The Black Donnelly Massacre takes the lives of five members of one family in Biddulph Township, Middlesex County, Ontario, Canada.
- February 24 – The SS Columbia, which will be the first outside usage of Thomas Edison's incandescent light bulb, is launched at the Delaware River Iron Ship Building and Engine Works of John Roach & Sons in Chester, Pennsylvania.
- March 31 – Wabash, Indiana becomes the first electrically lit city in the world.
- April – The government of Cape Colony sets a deadline for the Basuto people to surrender their weapons; non-compliance leads to the Basuto Gun War.
- April 18 – 1880 United Kingdom general election: William Ewart Gladstone defeats Benjamin Disraeli, to become Prime Minister for the second time.
- April 19 – The Prime Minister of Sweden, Louis De Geer, resigns over the defeat of a defense reform bill in the country's Riksdag; he is succeeded by Count Arvid Posse (1880–1883).
- April 27 – The Royal University of Ireland is founded by charter, allowing the Catholic University of Ireland to re-form as University College Dublin.
- May 2 – After having her lights installed by Edison's personnel, the SS Columbia is lit up for the first time at the foot of Wall Street, in New York City.
- May 13 – In Menlo Park, New Jersey, Thomas Edison performs the first test of his electric railway.
- June – The SS Columbia sets off on her maiden voyage around Cape Horn to Portland, Oregon, carrying 13 locomotives and 200 railcars.
- June 1 – Tinius Olsen is awarded a United States Patent, for the Little Giant Testing Machine.
- June 28 – Australian police capture bank robber Ned Kelly, after a gun battle at Glenrowan, Victoria.
- June 29 – France annexes Tahiti.
- July 14 – Dorchester Penitentiary opens in Canada.
- July 22 – Abdur Rahman Khan becomes Emir of Afghanistan.
- July 27 – Second Anglo-Afghan War – Battle of Maiwand: Afghan troops under Ayub Khan defeat British and Indian forces, under Brigadier General George Burrows.
- August 14 – Cologne Cathedral is completed, after construction began in 1248, 632 years earlier.
- August 24 – The SS Columbia completes her maiden voyage, arriving without incident in Portland, Oregon, after a stopover in San Francisco.
- August 26 – Competing circus owners P. T. Barnum and James A. Bailey sign a contract in Bridgeport, Connecticut to create the Barnum & Bailey Circus. In 1907, the circus will merge forces with another competitor, the Ringling Brothers Circus.
- September 1 – Second Anglo-Afghan War – Battle of Kandahar: General Frederick Roberts, commanding British forces, defeats the Afghan troops of Mohammad Ayub Khan, bringing an end to the war.