Events from the year 1845 in the United States.
Incumbents
Federal government
President: John Tyler (I-Virginia) (until March 4), James K. Polk (D-Tennessee) (starting March 4) Vice President: vacant (until March 4), George M. Dallas (D-Pennsylvania) (starting March 4) Chief Justice: Roger B. Taney (Maryland) Speaker of the House of Representatives: John Winston Jones (D-Virginia) (until March 4), John Wesley Davis (D-Indiana) (starting December 1) Congress: 28th (until March 4), 29th (starting March 4)
Events
January–March
January 1 – The Cobble Hill Tunnel in Brooklyn is completed. January 29 – "The Raven" by Edgar Allan Poe is published for the first time (New York Evening Mirror). February 1 – Anson Jones, President of the Republic of Texas, signs the charter officially creating Baylor University, which becomes the oldest university in the State of Texas operating under its original name. February 28 – The United States Congress approves the annexation of Texas. March 1 – President John Tyler signs a bill authorizing the United States to annex the Republic of Texas. March 3 Florida is admitted as the 27th U.S. state (see History of Florida). Postal reform act of Congress standardizes nationwide mail rates. March 4 The United States Congress passes legislation overriding a presidential veto for the first time. James K. Polk is sworn in as the 11th president of the United States, and George M. Dallas is sworn in as 11th vice president.
April–June
April 10 – The Great Fire of Pittsburgh destroys much of the city of Pittsburgh, Pennsylvania. April 21 – Peoria, Illinois is incorporated a city. May – Frederick Douglass's Narrative of the Life of Frederick Douglass, an American Slave, written by himself, is published by the Boston Anti-Slavery Society. May 23 -The New York City Police Department is formed.
July–September
July 4 – Near Concord, Massachusetts, Henry David Thoreau embarks on a 2-year experiment in simple living at Walden Pond (see Walden). July 19 – Great New York City Fire of 1845 breaks out in Lower Manhattan. July–August – In the United States Magazine and Democratic Review editor John L. O'Sullivan declares that foreign powers are trying to prevent American annexation of Texas in order to impede "the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions", the first use of the phrase "Manifest Destiny". August 28 – The journal Scientific American begins publication.
October–December
October 10 – In Annapolis, Maryland, the Best School (later renamed the United States Naval Academy) opens with 50 midshipmen students and 7 professors. October 13 – A majority of voters in the Republic of Texas approve a proposed constitution, that if accepted by the United States Congress, will make Texas a U.S. state. October 21 – The New York Herald becomes the first newspaper to mention the game of baseball. October 22 – The New York Morning News becomes the first newspaper to include a box-score of a baseball game. December 2 – Manifest Destiny: U.S. President James K. Polk announces to Congress that the Monroe Doctrine should be strictly enforced and that the United States should aggressively expand into the West. December 5 – The Templars of Honor and Temperance is founded in the United States. December 6 – Alpha Sigma Phi fraternity is founded. December 27 Anesthesia is used for childbirth for the first time (Dr. Crawford Long in Jefferson, Georgia). American journalist John L. O'Sullivan claims in a newspaper article (in connection with the annexation of the Oregon Country) that the United States has a "Manifest Destiny" to expand its borders, the second time he uses the term; it will have a huge influence on the American imperialistic movement of the 19th century. December 29 – Texas is admitted as the 28th U.S. state (see History of Texas).
Unknown date
Spaniards find Lost Dutchman Mine, Arizona.