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1997 (MCMXCVII)was a common year starting on Wednesday of the Gregorian calendar, the 1997th year of the Common Era (CE) and Anno Domini (AD) designations, the 997th year of the 2nd millennium, the 97th year of the 20th century, and the 8th year of the 1990s decade.
- March 4 – U.S. President Bill Clinton bans federal funding for any research on human cloning.
- March 7 – In Sri Lanka, the Tamil Tigers overrun a military base and kill at least 100.
- March 13
- March 16 – Sandline affair: On Bougainville Island, soldiers of commander Jerry Singirok arrest Tim Spicer and his mercenaries of the Sandline International.
- March 18 – The tail of a Russian An-24 charter plane breaks off while en route to Turkey, causing the plane to crash, killing all 50 on board, and resulting in the grounding of all An-24s.
- March 21 – In Zaire, Étienne Tshisekedi is appointed prime minister; he ejects supporters of Mobutu Sese Seko from his cabinet.
- March 22 – The Comet Hale–Bopp makes its closest approach to Earth.
- March 24 – The 69th Academy Awards, hosted by Billy Crystal, are held at the Shrine Auditorium in Los Angeles, with The English Patient winning Best Picture.
- March 24–26 – In San Diego, 39 Heaven's Gate cultists commit mass suicide at their compound.
- March 26 – Julius Chan resigns as prime minister of Papua New Guinea, ending the Sandline affair.
- March 30 – Channel 5 began broadcasting and was the fifth and final national terrestrial analogue network in the United Kingdom.
- May 2 – The Labour Party of the United Kingdom returns to power for the first time in 18 years, with Tony Blair becoming Prime Minister, in a landslide majority in the 1997 general election.
- May 3 – Katrina and the Waves win the Eurovision Song Contest 1997 for the UK with Love Shine a Light.
- May 9 – The first genetically modified three-parent baby is born.
- May 10 – The 7.3 Mw Qayen earthquake strikes eastern Iran with a maximum Mercalli intensity of X (Extreme). At least 1,567 were killed and 2,300 were injured.
- May 11 – IBM's Deep Blue defeats Garry Kasparov in the last game of the rematch, the first time a computer beats a chess World champion in a match.
- May 12
- The Russian–Chechen Peace Treaty is signed.
- An F1-rated tornado strikes downtown Miami, causing $525,000 in damages. Pictures and videos of this tornado made news headlines around the world.
- May 15 – The United States government acknowledges existence of the "Secret War" in Laos (1953–1975) during the Vietnam War, and dedicates the Laos Memorial in honor of Hmong and other "Secret War" veterans.
- May 16
- May 17 – Troops of Laurent Kabila march into Kinshasa.
- May 23 – Mohammad Khatami wins the 1997 Iranian presidential election and becomes the first Iranian Reformist president.
- May 25 – A military coup in Sierra Leone replaces President Ahmad Tejan Kabbah with Major Johnny Paul Koroma.
- May 27 – The second-deadliest tornado of the 1990s hits in Jarrell, Texas, killing 27 people.
- May 31 – The 13-kilometer Confederation Bridge, the world's longest bridge spanning ice-covered waters, opens between Prince Edward Island and New Brunswick, Canada.
- June 1
- June 2 – In Denver, Colorado, Timothy McVeigh is convicted on 15 counts of murder and conspiracy for his role in the 1995 Oklahoma City bombing.
- June 10 – Khmer Rouge leader Pol Pot orders the killing of his defense chief, Son Sen, and 11 of Sen's family members, before Pol Pot flees his northern stronghold.
- June 11 – In the United Kingdom, the House of Commons votes for a total ban on handguns.
- June 13 – A jury sentences Timothy McVeigh to death for his part in the 1995 Oklahoma City bombing.
- June 16 – About 50 people are killed in the Daïat Labguer (M'sila) massacre in Algeria.
- June 25
- June 26 – Bertie Ahern is appointed as the 10th Taoiseach of the Republic of Ireland and Mary Harney is appointed as the 16th, and first female, Tánaiste, after their parties, Fianna Fáil and the Progressive Democrats respectively, win the 1997 General Election.
- June 26 – Bloomsbury Publishing publishes J. K. Rowling's Harry Potter and the Philosopher's Stone in London.
- July – The 1997 Central European flood occurs across Poland, Germany, and the Czech Republic.
- July 1 – The United Kingdom hands sovereignty of Hong Kong to the People's Republic of China.
- July 2 – The Bank of Thailand floats the baht, triggering the Asian financial crisis
- July 4 – NASA's Pathfinder space probe lands on the surface of Mars.
- July 5
- July 8 – NATO invites the Czech Republic, Hungary, and Poland to join the alliance in 1999.
- July 10 – In London, scientists report their DNA analysis findings from a Neanderthal skeleton, which support the out of Africa theory of human evolution, placing an "African Eve" at 100,000 to 200,000 years ago.
- July 11 – Thailand's worst hotel fire at Pattaya kills 90.
- July 13 – The remains of Che Guevara are returned to Cuba for burial, alongside some of his comrades. Guevara and his comrades were executed on October 9 1967 in Bolivia.
- July 15 – Spree killer Andrew Cunanan shoots fashion designer Gianni Versace dead outside Versace's Miami residence.
- July 17 – The F. W. Woolworth Company closes after 117 years in business.
- July 25 – K. R. Narayanan is sworn in as India's 10th president and the first member of the Dalit caste to hold this office.
- July 27 – About 50 are killed in the Si Zerrouk massacre in Algeria.
- July 30 – 18 people are killed in the Thredbo landslide in the Snowy Mountains resort in Australia.
- September 1 – Dublin Regulation on treatment of applications for right of asylum under European Union law first comes into force.
- September 5
- September 6 – The funeral of Diana, Princess of Wales, takes place at Westminster Abbey, watched by over two billion people worldwide.
- September 11 – Scotland votes in favour of a devolved Parliament forming the Scottish Parliament less than two years later
- September 13 – Iraq disarmament crisis: An Iraqi military officer attacks an UNSCOM weapons inspector on board an UNSCOM helicopter, while the inspector attempts to take photographs of unauthorized movement of Iraqi vehicles inside a site designated for inspection.
- September 15 – The Norwegian parliamentary election was held in Norway.
- September 17 – Iraq disarmament crisis: While waiting for access to a site, UNSCOM inspectors witness and videotape Iraqi guards moving files, burning documents, and dumping waste cans into a nearby river.
- September 18
- September 19 – 53 are killed in the Guelb El-Kebir massacre in Algeria.
- September 21 – The Islamic Salvation Army, the Islamic Salvation Fronts' armed wing, declares a unilateral ceasefire in Algeria.
- September 25 – Iraq disarmament crisis: UNSCOM inspector Dr. Diane Seaman catches several Iraqi men sneaking out the back door of an inspection site, with log books for the creation of prohibited bacteria and chemicals.
- September 26
- December 1 – In the Indian state of Bihar, Ranvir Sena attacks the CPI(ML) Party Unity stronghold Lakshmanpur-Bathe, killing 63 lower caste people.
- December 3 – In Ottawa, Ontario, Canada, representatives from 121 countries sign a treaty prohibiting the manufacture and deployment of anti-personnel land mines. However, the United States, the People's Republic of China, Russia, South Korea and 32 other nations do not sign and/or ratify the treaty.
- December 10 – The capital of Kazakhstan is moved from Almaty to Astana.
- December 11 – The Kyoto Protocol is adopted by a United Nations committee.
- December 19
- December 21 – beats Australia 6–0 in the Confederations Cup final.
- December 24 – 50–100 villagers are killed in the Sid El-Antri massacre in Algeria.
- December 27 – Ulster loyalist paramilitary leader Billy Wright is assassinated in Northern Ireland, inside Long Kesh prison.
- December 29 – Hong Kong begins to kill all the chickens within its territory (1.25 million) to stop the spread of a potentially deadly influenza strain.
- December 30 – Wilaya of Relizane massacres of December 30, 1997: In the worst incident in Algeria's insurgency, 400 are killed from four villages in the wilaya of Relizane.
- The Toyota Prius, the first hybrid vehicle to go into full production, is unveiled in Japan on October 24, and goes on sale in Japan on December 9. It comes to U.S. showrooms on July 11, 2000.