Upvote:8
Legally, a territory is directly governed by the federal government, and can't pick a side. There's no possibility of "withdrawing from the Union" or equivalent.
In practice, things were a bit different:
- Colorado Territory: Mixed sympathies, sparse population, and no overt declarations.
- Confederate Arizona: The southern portions of Arizona and New Mexico Territories supported the Confederacy and established a pro-Confederacy government in Tucson.
- Dakota Territory: Very sparsely populated.
- Idaho Territory: The eastern portion sympathized with the Confederacy; the western portion was pro-Union. This was the impetus for dividing off the eastern section into Montana Territory.
- Indian Territories: The tribes of the Indian Territories allied themselves with the Confederacy.
- Montana Territory: Confederate sympathies, but no declaration of support.
- Nebraska Territory: Strongly pro-Union.
- Utah Territory: Anti-Union, but not pro-Confederate.
- Washington Territory: Generally pro-Union.
Overall, approximately two territories joined the Confederacy, while Nebraska contributed a large contingent to the Union army. The other territories had general sympathies towards one side or the other, but didn't explicitly pick a side, becoming Union by default.