January 1, 1873 – Japan begins using the Gregorian calendar.

January 17, 1873 – A group of Modoc warriors defeats the United States Army in the First Battle of the Stronghold, a part of the Modoc War.

February 11, 1873 – King Amadeus I of Spain abdicates.

February 20, 1873 – The University of California opens its first medical school in San Francisco, California.

April 4, 1873 – The Kennel Club is founded, the oldest and first official registry of purebred dogs in the world.

May 20, 1873 – Levi Strauss and Jacob Davis receive a U.S. patent for blue jeans with copper rivets.

August 4, 1873 – Indian Wars: whilst protecting a railroad survey party in Montana, the United States 7th Cavalry, under Lieutenant Colonel George Armstrong Custer clashes for the first time with the Sioux near the Tongue River; only one man on each side is killed.

August 23, 1873 – Albert Bridge in Chelsea, London opened.

August 30, 1873 – Austrian explorers Julius von Payer and Karl Weyprecht discover the archipelago of Franz Joseph Land in the Arctic Sea.

September 1, 1873 – Cetshwayo ascends to the throne as king of the Zulu nation following the death of his father Mpande.

January 2, 1873 – Thérèse of Lisieux, French Roman Catholic nun (d. 1897)

January 28, 1873 – Colette, French writer (d. 1954)

February 25, 1873 – Enrico Caruso, Italian tenor (d. 1921)

March 19, 1873 – Max Reger, German composer (d. 1916)

April 10, 1873 – Alfred Kubin, Austrian expressionist illustrator and writer (d. 1959)

June 29, 1873 – Leo Frobenius, German ethnologist and archaeologist (d. 1938)

August 19, 1873 – Fred Stone, American actor (d. 1959)

October 9, 1873 – Karl Schwarzschild, German physicist and astronomer (d. 1916)

November 16, 1873 – W. C. Handy, American composer (d. 1958)

December 7, 1873 – Willa Cather, American novelist (d. 1947)