1848

January 24 - California gold rush: James W. Marshall finds gold at Sutter's Mill, in Coloma, near Sacramento
January 26 - Henry David Thoreau addresses the Concord Lyceum with "The Rights and Duties of the Individual in Relation to Government" (which later came to be known as ).
February 2 - Mexican-American War: The Treaty of Guadalupe Hidalgo is signed, ending the war.
February 2 - California Gold Rush: The first ship with Chinese emigrants seeking fortune in California's gold country arrive in San Francisco.
February 21 - Karl Marx publishes The Communist Manifesto.
February 24 - Abdication of Le Roi-Citoyen (citizen king) Louis Philippe, King of the French and the proclamation of the Second Republic.
March 7 - The Great Mahele (land division) is signed in Hawaii.
March 10 - The Treaty of Guadalupe Hidalgo is ratified by the United States Senate, ending the Mexican-American War.
March 15 - revolution breaks out in Pest. The Habsburg rulers are compelled to meet the demands of the Reform party.
March 20 - King Ludwig I of Bavaria abdicates
March 29 - An upstream ice jam stops almost all water flow over Niagara Falls.
May 19 - Mexican-American War: Treaty of Guadalupe Hidalgo - Mexico ratifies the treaty thus ending the war and ceding Texas, California and most of Arizona and New Mexico to the United States for $15 million dollars.
May 29 - Wisconsin is admitted as the 30th U.S. state.
July 19 - Women's rights: The two day Women's Rights Convention opens in Seneca Falls, New York and the "Bloomers" are introduced at the feminist convention.
July 29 - Irish Potato Famine: Tipperary Revolt - In Tipperary, an unsuccessful nationalist revolt against British rule is put-down by a government police force.
August 19 - California Gold Rush: The New York Herald breaks the news to the East Coast of the United States, that there is a gold rush in California (although the rush started in January).
November 1 - In Boston, Massachusetts, the first medical school for women, The Boston Female Medical School (which later merged with Boston University School of Medicine), opens.
November 3 - Greatly revised Dutch constitution proclaimed
November 7 - U.S. presidential election, 1848: Zachary Taylor is elected president in the first US presidential election held in every state on the same day.
December 2 - Ferdinand I, Emperor of Austria, abdicates in favor of his nephew, Franz Josef I.
December 10 - Prince Louis-Napoleon Bonaparte elected first president of the French Second Republic.
December 20 - President Bonaparte takes his Oath of Office in front of the French National Assembly.
Wave of republican and democratic uprisings throughout Europe, mostly unsuccessful (see Revolution of 1848).
Women hold Seneca Falls Convention in New York.
Associated Press is founded.
Boston Public Library is founded by an act of the Great and General Court of Massachusetts,
First railway in Spain is opened, with line Barcelona to MatarÃÂÃÂ³ (circa 40 km).
Illinois and Michigan Canal is completed.
Independent Republic of Yucatan joins Mexico in exchange for Mexican help in suppressing revolt by Maya Indians.
Serfdom is abolished in Austro-Hungarian Empire.
John Bird Sumner becomes archbishop of Canterbury.
British, Dutch, and German governments lay claim to New Guinea.
Admiral Nevelskoi explores Strait of Tartary.
Dunedin, New Zealand is founded.
University of Ottawa is founded.
University of Mississippi is founded.
University of Wisconsin, Madison is founded.
Geneva College in Pennsylvania is founded.
Holmes County, Florida is created.
Elizabeth Gaskell publishes Mary Barton anonymously.
Henrik Ibsen publishes first play Catilina.
Ivar Aasen publishes Grammar of the Norwegian Dialects.
Robert Schumann composes opera Genoveva.
Richard Wagner begins writing libretto that will become The Ring of the Nibelung.