For a group of workers bargaining collectively, see labor union.
The American states which had already been admitted but did not secede in 1861 are collectively known as the Union. In alphabetical order they were California, Connecticut, Delaware, Illinois, Indiana, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, Washington and Wisconsin, for a total of 23. During the war, Kansas, Nevada and West Virginia were added for a wartime high of 26, as against 11 for the Confederacy. The Union's demographic and industrial advantage was somewhat greater than the 2.5 to 1 ratio of states would suggest.
Unionism was the support for remaining in the Union among the people of states where slavery was legal. It was sufficiently strong in Delaware, Kentucky, Maryland and Missouri to keep those states from seceding, and inspired the Republican Party to change its name to Unionist for the 1864 Presidential election only, when President Abraham Lincoln chose Tennessee Governor Andrew Johnson as his running mate. Persons originating in the other 22 states of the Union have forever after been known in the South as Yankees, although the term is sometimes also misused to describe people from Nebraska, North Dakota and South Dakota.