1843 1844 1845 - 1846 - 1847 1848 1849
| Decades: |
1810s 1820s 1830s - 1840s - 1850s 1860s 1870s
| Centuries: |
18th century - 19th century - 20th century
- January 5 - The United States House of Representatives votes to stop sharing the Oregon Territory with the United Kingdom
- February 5 - 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.
- March 10 - Prince Osahito, fourth son of deceased Emperor Ninko of Japan, becomes Emperor Komei of Japan.
- April 25 - Mexican-American War: Open conflict begins over border disputes of Texas' boundaries.
- April 27 - The first arrival of a train to Celje.
- May 8 - Mexican-American War: The Battle of Palo Alto - Zachary Taylor defeats a Mexican force north of the Rio Grande at Palo Alto, California 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 10 - Mexican-American War: The California Republic declares independence from Mexico.
- June 10 - Grinnell College: The first American college or university to the West of the Mississippi River is founded.
- June 14 - Bear Flag Revolt begins - American settlers in Sonoma, California start a rebellion against Mexico and proclaim the California Republic.
- June 15 - The Oregon Treaty establishes the 49th parallel as the border between the United States and Canada, from the Rocky Mountains to the Strait of Juan de Fuca.
- 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.
- September 23 – Neptune found (thought not named that for years)
- December 28: Iowa is admitted as the 29th U.S. state.
- Potato crop fails in Ireland
- Electric Telegraph Company founded in Britain
- Liberia declares independence as a republic
- Elias Howe patents the sewing machine
- Mexican-American War (1846-1848)
- 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
- November 25 - Carrie Nation, advocate of temperence movement.
- June 1 - Pope Gregory XVI
- June 8 - [[Rodolphe T�pffer]], Swiss teacher, author, painter and caricature artist. He is also considered to be the first modern comic creator.
- Emperor Ninko of Japanaf:1846
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