1846 in the United States
Events from the year 1846 in the United States. In this year, the United States declares war on Mexico, starting the Mexican–American War.
September 21–24: Battle of Monterrey (Mexican–American War).
1845 in the United States
Events from the year 1845 in the United States.
March 4: James K. Polk becomes the 11th U.S. president
George M. Dallas becomes the 11th U.S. vice president
December 27: The term "Manifest Destiny" is influentially used by John L. O'Sullivan (the concept is depicted in this 1872 painting by John Gast)
Andrew Jackson