A state designation for a US volunteer regiment doesn't mean all the troops came from that state. The 51st Indiana had a fair amount of recruits from North Carolina. The 6th Kentucky had recruits from Tenn. The 7th Kan Cav USV and companies from Ill and OH. The 1st Ark USV Cav had Mo recruits. Confederate Regiments at least some had recruits who were recent arrivals from northern states see the book Wilsons Creek by Piston and Hatcher. See the diary of Pomoroy Fletcher for the 7th Kan and google unionists in NC during the civil war and 1st Ark USV. Keep in mind that most CW regiments suffered high rates of death, disease and desertion so there were always openings. The Union in 1864 was even recruiting captured Confederate soldiers to fight Indians.

Leonard