Editing 1840s (section)

===== Settlement =====
[[File:USA Territorial Growth 1850.jpg|thumb|300px|United States territorial growth from 1840 to 1850]]
* [[May 11]], [[1841]] – [[Charles Wilkes|Lt. Charles Wilkes]] lands at [[Fort Nisqually]] in [[Puget Sound]].
* [[August 4]], [[1842]] – The [[Armed Occupation Act]] is signed, providing for the armed occupation and settlement of the unsettled part of the Peninsula of [[East Florida]].
* [[August 9]], [[1842]] – The [[Webster–Ashburton Treaty]] is signed, settling the dispute over the location of the [[Maine]]–[[New Brunswick]] [[Canada–United States border|border between the United States and Canada]], and establishing the United States–Canada border east of the [[Rocky Mountains]].
* [[May 22]], [[1843]] – The first major [[wagon train]] headed for the American Northwest sets out with one thousand pioneers from [[Elm Grove, Missouri]], on the [[Oregon Trail]].
* [[March 3]], [[1845]] – [[Florida]] is admitted as the 27th [[U.S. state]].
* [[December 2]], [[1845]] – [[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 29]], [[1845]] – [[Texas]] is admitted as the 28th [[U.S. state]].
* [[June 15]], [[1846]] – The [[Oregon Treaty]] establishes the [[49th parallel north|49th parallel]] as the border between the United States and Canada, from the [[Rocky Mountains]] to the [[Strait of Juan de Fuca]].
* [[1846]] – The portion of the [[Washington, D.C.|District of Columbia]] that was ceded by [[Virginia]] in [[1790]] is re-ceded to [[Virginia]].
* [[December 28]], [[1846]] – [[Iowa]] is admitted as the 29th [[U.S. state]].
* [[July 24]], [[1847]] – After 17 months of travel, [[Brigham Young]] leads 148 [[Mormon pioneers]] into [[Salt Lake Valley]], resulting in the establishment of [[Salt Lake City]].[[File:Flag of Wisconsin.svg|thumb|[[May 29]]: [[Wisconsin]] admitted as the 30th [[U.S. state]].]]
* [[May 29]], [[1848]] – [[Wisconsin]] is admitted as the 30th [[U.S. state]].
* [[1848]] – The [[Illinois and Michigan Canal]] is completed.
* [[March 3]], [[1849]] – [[Minnesota]] becomes a [[Territories of the United States|United States territory]]