January
January 3 – Benito Mussolini (Il Duce) announces he is taking dictatorial powers over Italy.
January 5 – Nellie Tayloe Ross becomes the first female governor (Wyoming) in the United States. Twelve days later, Ma Ferguson becomes first female governor of Texas.
January 27–February 1 – The 1925 serum run to Nome (the "Great Race of Mercy") relays diphtheria antitoxin by dog sled across the U.S. territory of Alaska, to combat an epidemic.
February
February 15 – The Alice Comedy Alice Solves the Puzzle is released at 6:54 a.m. by Disney Brothers Cartoon Studio, introducing Bootleg Pete (an early prototype for Pegleg Pete) for the first time.
February 21 – The New Yorker magazine publishes its first issue.
February 25 – Art Gillham records for Columbia Records the first Western Electric masters to be commercially released.
February 28 – The 1925 Charlevoix-Kamouraska earthquake strikes northeastern North America.
March
March 4
İsmet İnönü is appointed as the prime minister in Turkey (Turkey's 4th and İnönü's 3rd government).
The inauguration of Calvin Coolidge as President of the United States becomes the first to be broadcast on radio.
March 6 – Pionerskaya Pravda, one of the oldest children's newspapers in Europe, is founded in the Soviet Union.
March 9–May 1 – Pink's War: The British Royal Air Force bombards mountain strongholds of Mahsud tribesmen in South Waziristan.
March 15 – The Phi Lambda Chi fraternity (original name "The Aztecs") is founded on the campus of Arkansas State Teacher's College in Conway, Arkansas (now the University of Central Arkansas).
March 18 – The Tri-State Tornado, the deadliest in U.S. history, rampages through Missouri, Illinois, and Indiana, killing 695 people and injuring 2,027. It hits the towns of Murphysboro, Illinois; Gorham, Illinois; Ellington, Missouri; and Griffin, Indiana.
March 21 – Tennessee Governor Austin Peay signs the Butler Act, prohibiting the teaching of evolution in the state's public schools.
March 31 – Radio station WOWO in Ft. Wayne, Indiana begins broadcasting.
April
April–October – The Exposition Internationale des Arts Décoratifs et Industriels Modernes is held in Paris, giving a name to the Art Deco style.
April 1
Frank Heath and his horse Gypsy Queen leave Washington, D.C. to begin a two-year journey to visit all 48 states.
The Patent and Trademark Office is transferred to the Department of Commerce.
April 3 – The United Kingdom, South Africa and Australia return to the (bullion) gold standard.
April 10 – F. Scott Fitzgerald publishes The Great Gatsby.
April 15 – Fritz Haarmann, a serial killer convicted of the murder of 24 boys and young men, is beheaded in Germany.
April 16 – The Communist assault on St. Nedelya Church claims roughly 150 lives in Sofia, Bulgaria.
April 20 – Iranian forces of Rezā Shāh occupy Ahwaz, and arrest Sheikh Khaz'al.
May
May 1
The mausoleums in al-Baqi are destroyed by King Ibn Saud (Lanati). In the same year, he also demolishes the tombs of holy persons at Mualla Cemetery in Mecca where Muhammad's first wife Khadijah, his grandfather and other ancestors are buried. This happens despite protests by the international Islamic community.
May 5
Scopes Trial: Dayton, Tennessee, biology teacher John Scopes is arrested for teaching Charles Darwin's Theory of Evolution.
The General Election Law is passed in Japan.
May 8 – Tom Lee rescues 32 people from the M.E. Norman, a sinking steamboat.
May 25
Scopes Trial: John T. Scopes is indicted for teaching Darwin's theory of evolution.
The National Forensic League is founded.
May 29 – British explorer Percy Fawcett sends a last telegram to his wife, before he disappears in the Amazon.
June
June 1 – Percy and Florence Arrowsmith are married. This couple, who celebrated their 80th wedding anniversary June 1, 2005 (Percy aged 105, and wife Florence 100), are acknowledged by the Guinness Book of Records as record-holders for the longest marriage for a living couple and the greatest aggregate age of a married couple.
June 6 – The Chrysler Corporation is founded by Walter Percy Chrysler.
June 13 – Charles Francis Jenkins achieves the first synchronized transmission of pictures and sound, using 48 lines, and a mechanical system. A 10-minute film of a miniature windmill in motion is sent across 5 miles from Anacostia to Washington, D.C. The images are viewed by representatives of the National Bureau of Standards, the U.S. Navy, the Commerce Department, and others. Jenkins calls this "the first public demonstration of radiovision".
June 14
The Aristotle University of Thessaloniki in Greece is founded.
The Turkish football club Göztepe is founded.
June 29 – Santa Barbara Earthquake of 1925: A 6.8 earthquake destroys downtown Santa Barbara, California.
July
July 9 – In Dublin, Ireland, Oonagh Keogh becomes the first female member of a stock exchange in the world.
July 10
Scopes Trial: In Dayton, Tennessee, the so-called "Monkey Trial" begins with John T. Scopes, a young high school science teacher, accused of teaching evolution in violation of a Tennessee state law.
Meher Baba begins his 44-year silence.
July 18 – Adolf Hitler publishes his personal manifesto Mein Kampf.
July 21 – Scopes Trial: In Dayton, Tennessee, high school biology teacher John T. Scopes is found guilty of teaching evolution in class and fined $100.
July 25 – The Telegraph Agency of the Soviet Union (TASS) is established.
August
August 8 – The Ku Klux Klan demonstrates its popularity by holding a parade in Washington DC; as many as 40,000 male and female members of the Klan march down Pennsylvania Avenue. In 1925, an estimated 5,000,000 members belong to the Ku Klux Klan, making it the largest fraternal organization in the United States.
August 14 – The original Hetch Hetchy Moccasin Powerhouse is completed and goes on line.
August 25 – The French evacuate the Ruhr region of Germany.
September
September 3 – The U.S. dirigible Shenandoah breaks up near Caldwell, Ohio; 14 crewmen are killed.
September 27 – Feast of the Cross according to the Old Calendar; A celestial cross appears over Athens, Greece, while the Greek Police pursues a group of Greek Old Calendarists. The phenomenon lasts for half an hour.
October
October – The major money forgery and fraud of Alves Reis is exposed in Portugal.
October 1 – Mount Rushmore National Memorial is dedicated in South Dakota.
Locarno Treaties with Gustav Stresemann, Austen Chamberlain and Aristide Briand
October 2 – In London
John Logie Baird successfully transmits the first television pictures with a greyscale image. The city's first enclosed double-decker buses are introduced.
October 5–16 – The Locarno Treaties are negotiated.
October 8 – Cubana de Aviación is founded.
November
November 5 – Secret agent Sidney Reilly is executed by the OGPU, the secret police of the Soviet Union.
November 24 – The silent film Hussar of the Dead is released in Santiago de Chile.
November 26 – Prajadhipok (Rama VII) is crowned as King of Siam.
November 28 – The weekly country music-variety radio program Grand Ole Opry is first broadcast on WSM radio in Nashville, Tennessee, as the "WSM Barn Dance".
December
December 1 – The Locarno Treaties are signed in London.
December 11 – Pope Pius XI's encyclical Quas Primas, on the Feast of Christ the King, is promulgated.
Reza Shah
December 16
Reza Shah becomes shah of Persia.
Alpha Phi Omega, a National service fraternity, is founded at Lafayette College.
Colombo Radio launches in Ceylon; the station is subsequently known as Radio Ceylon.
December 25 – IG Farben is formed by the merger of six chemical companies in Germany.
December 26 – The Great Sphinx of Giza is unearthed at the start of a complete excavation.
January 3 – Benito Mussolini (Il Duce) announces he is taking dictatorial powers over Italy.
January 5 – Nellie Tayloe Ross becomes the first female governor (Wyoming) in the United States. Twelve days later, Ma Ferguson becomes first female governor of Texas.
January 27–February 1 – The 1925 serum run to Nome (the "Great Race of Mercy") relays diphtheria antitoxin by dog sled across the U.S. territory of Alaska, to combat an epidemic.
February
February 15 – The Alice Comedy Alice Solves the Puzzle is released at 6:54 a.m. by Disney Brothers Cartoon Studio, introducing Bootleg Pete (an early prototype for Pegleg Pete) for the first time.
February 21 – The New Yorker magazine publishes its first issue.
February 25 – Art Gillham records for Columbia Records the first Western Electric masters to be commercially released.
February 28 – The 1925 Charlevoix-Kamouraska earthquake strikes northeastern North America.
March
March 4
İsmet İnönü is appointed as the prime minister in Turkey (Turkey's 4th and İnönü's 3rd government).
The inauguration of Calvin Coolidge as President of the United States becomes the first to be broadcast on radio.
March 6 – Pionerskaya Pravda, one of the oldest children's newspapers in Europe, is founded in the Soviet Union.
March 9–May 1 – Pink's War: The British Royal Air Force bombards mountain strongholds of Mahsud tribesmen in South Waziristan.
March 15 – The Phi Lambda Chi fraternity (original name "The Aztecs") is founded on the campus of Arkansas State Teacher's College in Conway, Arkansas (now the University of Central Arkansas).
March 18 – The Tri-State Tornado, the deadliest in U.S. history, rampages through Missouri, Illinois, and Indiana, killing 695 people and injuring 2,027. It hits the towns of Murphysboro, Illinois; Gorham, Illinois; Ellington, Missouri; and Griffin, Indiana.
March 21 – Tennessee Governor Austin Peay signs the Butler Act, prohibiting the teaching of evolution in the state's public schools.
March 31 – Radio station WOWO in Ft. Wayne, Indiana begins broadcasting.
April
April–October – The Exposition Internationale des Arts Décoratifs et Industriels Modernes is held in Paris, giving a name to the Art Deco style.
April 1
Frank Heath and his horse Gypsy Queen leave Washington, D.C. to begin a two-year journey to visit all 48 states.
The Patent and Trademark Office is transferred to the Department of Commerce.
April 3 – The United Kingdom, South Africa and Australia return to the (bullion) gold standard.
April 10 – F. Scott Fitzgerald publishes The Great Gatsby.
April 15 – Fritz Haarmann, a serial killer convicted of the murder of 24 boys and young men, is beheaded in Germany.
April 16 – The Communist assault on St. Nedelya Church claims roughly 150 lives in Sofia, Bulgaria.
April 20 – Iranian forces of Rezā Shāh occupy Ahwaz, and arrest Sheikh Khaz'al.
May
May 1
The mausoleums in al-Baqi are destroyed by King Ibn Saud (Lanati). In the same year, he also demolishes the tombs of holy persons at Mualla Cemetery in Mecca where Muhammad's first wife Khadijah, his grandfather and other ancestors are buried. This happens despite protests by the international Islamic community.
May 5
Scopes Trial: Dayton, Tennessee, biology teacher John Scopes is arrested for teaching Charles Darwin's Theory of Evolution.
The General Election Law is passed in Japan.
May 8 – Tom Lee rescues 32 people from the M.E. Norman, a sinking steamboat.
May 25
Scopes Trial: John T. Scopes is indicted for teaching Darwin's theory of evolution.
The National Forensic League is founded.
May 29 – British explorer Percy Fawcett sends a last telegram to his wife, before he disappears in the Amazon.
June
June 1 – Percy and Florence Arrowsmith are married. This couple, who celebrated their 80th wedding anniversary June 1, 2005 (Percy aged 105, and wife Florence 100), are acknowledged by the Guinness Book of Records as record-holders for the longest marriage for a living couple and the greatest aggregate age of a married couple.
June 6 – The Chrysler Corporation is founded by Walter Percy Chrysler.
June 13 – Charles Francis Jenkins achieves the first synchronized transmission of pictures and sound, using 48 lines, and a mechanical system. A 10-minute film of a miniature windmill in motion is sent across 5 miles from Anacostia to Washington, D.C. The images are viewed by representatives of the National Bureau of Standards, the U.S. Navy, the Commerce Department, and others. Jenkins calls this "the first public demonstration of radiovision".
June 14
The Aristotle University of Thessaloniki in Greece is founded.
The Turkish football club Göztepe is founded.
June 29 – Santa Barbara Earthquake of 1925: A 6.8 earthquake destroys downtown Santa Barbara, California.
July
July 9 – In Dublin, Ireland, Oonagh Keogh becomes the first female member of a stock exchange in the world.
July 10
Scopes Trial: In Dayton, Tennessee, the so-called "Monkey Trial" begins with John T. Scopes, a young high school science teacher, accused of teaching evolution in violation of a Tennessee state law.
Meher Baba begins his 44-year silence.
July 18 – Adolf Hitler publishes his personal manifesto Mein Kampf.
July 21 – Scopes Trial: In Dayton, Tennessee, high school biology teacher John T. Scopes is found guilty of teaching evolution in class and fined $100.
July 25 – The Telegraph Agency of the Soviet Union (TASS) is established.
August
August 8 – The Ku Klux Klan demonstrates its popularity by holding a parade in Washington DC; as many as 40,000 male and female members of the Klan march down Pennsylvania Avenue. In 1925, an estimated 5,000,000 members belong to the Ku Klux Klan, making it the largest fraternal organization in the United States.
August 14 – The original Hetch Hetchy Moccasin Powerhouse is completed and goes on line.
August 25 – The French evacuate the Ruhr region of Germany.
September
September 3 – The U.S. dirigible Shenandoah breaks up near Caldwell, Ohio; 14 crewmen are killed.
September 27 – Feast of the Cross according to the Old Calendar; A celestial cross appears over Athens, Greece, while the Greek Police pursues a group of Greek Old Calendarists. The phenomenon lasts for half an hour.
October
October – The major money forgery and fraud of Alves Reis is exposed in Portugal.
October 1 – Mount Rushmore National Memorial is dedicated in South Dakota.
Locarno Treaties with Gustav Stresemann, Austen Chamberlain and Aristide Briand
October 2 – In London
John Logie Baird successfully transmits the first television pictures with a greyscale image. The city's first enclosed double-decker buses are introduced.
October 5–16 – The Locarno Treaties are negotiated.
October 8 – Cubana de Aviación is founded.
November
November 5 – Secret agent Sidney Reilly is executed by the OGPU, the secret police of the Soviet Union.
November 24 – The silent film Hussar of the Dead is released in Santiago de Chile.
November 26 – Prajadhipok (Rama VII) is crowned as King of Siam.
November 28 – The weekly country music-variety radio program Grand Ole Opry is first broadcast on WSM radio in Nashville, Tennessee, as the "WSM Barn Dance".
December
December 1 – The Locarno Treaties are signed in London.
December 11 – Pope Pius XI's encyclical Quas Primas, on the Feast of Christ the King, is promulgated.
Reza Shah
December 16
Reza Shah becomes shah of Persia.
Alpha Phi Omega, a National service fraternity, is founded at Lafayette College.
Colombo Radio launches in Ceylon; the station is subsequently known as Radio Ceylon.
December 25 – IG Farben is formed by the merger of six chemical companies in Germany.
December 26 – The Great Sphinx of Giza is unearthed at the start of a complete excavation.