1846

January 5 - The United States House of Representatives votes to stop sharing the Oregon Territory with the United Kingdom
February 5 - The The Oregon Spectator becomes the first newspaper on the Pacific coast of the United States.
February 10 - Many Mormons begin their migration west from Nauvoo, Illinois to Great Salt Lake led by Brigham Young
February 19 - In Austin, Texas the newly-formed Texas state government is officially installed.
April 25 - Mexican-American War: Open conflict begins over border disputes of Texas' boundaries.
May 8 - Mexican-American War: The Battle of Palo Alto - Zachary Taylor defeats a Mexican force north of the Rio Grande at Palo Alto, Texas in the first major battle of the war.
May 13 - Mexican-American War: The United States declares war on Mexico.
May 17 - The Saxophone is patented by Adolphe Sax
June 21 - Pope Pius IX ascends to the Holy See.
July 7 - Acting on instructions from Washington, DC, Commodore John Drake Sloat orders his troops to occupy Monterey and Yerba Buena thus beginning the United States annexation of California.
December 28: Iowa is admitted as the 29th U.S. state.
Emperor Komei ascends to the throne of Japan
Potato crop fails in Ireland

Ongoing events

1846 in literature:
- The Devil's Pond - George Sand
Strauss's Life of Jesus which inaugurates the 2nd Quest of the Historical Jesus
April 27: The first arrival of a train to Celje.
June 19: first baseball game under recognizable modern rules.
September 23: Discovery of Neptune by German astronomer Johann Gottfried Galle.

February 9 - Wilhelm Maybach, designer of engines and cars, industrialist (+ 1929)
February 18 - Wilson Barrett, actor
February 26 - Buffalo Bill, pioneer and officer, hunter and carny (+ 1917)
April 4 - Comte de Lautreamont, French poet and writer. (+ 1870)
May 25 - Princess Helena of the United Kingdom, third daughter of Queen Victoria