Northern United States

===American Civil War===
{{main|Union (American Civil War)}}
[[File:US map 1864 Civil War divisions.svg|thumb|Map of the division of the states during the [[American Civil War]] (1861–1865); states in blue represent northern [[Union (American Civil War)|Union]] states, those in light blue representing five largely Union-supporting border southern states that permitted slavery, known as [[border states (Civil War)|border states]], and both [[Missouri]] and [[Kentucky]], which had competing Confederate and Unionist governments, and states in red representing southern seceded states, known as the [[Confederate States of America]] prior to the end of the [[American Civil War]]]]
During the [[American Civil War]] (1861–1865), the Northern states comprised the U.S. states that supported the United States of America, referred to as the [[Union (American Civil War)|Union]]. In this context, "the North" is synonymous with the Union, while "the South" refers to the states that seceded from the U.S. in order to form the [[Confederate States of America]].

There is, however, some historical disagreement as to exactly which states comprised the North in the context of the Civil War as five [[slavery in the United States|slave-holding]] states largely remained with the Union: the southern [[Border states (American Civil War)|border states]] of [[Missouri]], [[Kentucky]], [[West Virginia]], [[Maryland]], and [[Delaware]], along with the disputed [[Indian Territory]], though [[Missouri]] and [[Kentucky]] had dual competing Confederate and Unionist governments with the [[Confederate government of Kentucky]] and the [[Confederate government of Missouri]] and the Confederacy controlled more than half of Kentucky and the southern portion of Missouri early in the war. The Confederacy largely lost control in both states after 1862; depending on the source, some of these states and territories may be included in either region.<ref>{{cite web|url=https://www.britannica.com/EBchecked/topic/418524/the-North |publisher=[[Encyclopædia Britannica Online]] |title= the North (region, United States)|year=2009 |access-date= 2009-10-27}}</ref>