Richard; not to belabor a point but to bring it forward as a discussion and hopefully a bit of learning for many that may stumble upon us. During the Civil War most of the units were Militias. Lincoln called upon the states to mobilize their State Militias for the war. Some states such as Ohio fielded such large militias like the Ohio Volunteer Infantry that they were armies in their own right. The First Iowa Volunteer Cavalry was a militia unit raised early in 1861, though it was attached to Union command early on it was never a regular US Army unit. We often forget that most of the units on both sides were citizen soldiers with little to brief training functioning with elected officers not professional soldiers. Think of your local National Guard unit compared to a Army Reserve unit today, similar but clearly different critters.
With all that said Missouri is "special" in that it had even more convoluted organizations. Price was appointed by Fox to lead the Missouri militia we know as the Missouri State Guard. This was countered by many pro Union volunteer Home Guard units. Then we get into the Enrolled Enlisted Militia, Provisional EEM, MSM and other ad hoc structures that were unique to Missouri.