One last thing I meant to note. When I was doing my grad work in the mid-90's, I had to do a project for statistical analysis. I chose a study of the 4th Arkansas Mounted Infantry (thanks to that Congressional Record listing of 1893) since I had a pretty full roster of the unit.
I was able to find about 298 or so of the men of the 4th in the 1860 Census for Arkansas, which gave me a great sample of who made up the unit. They were farmers, laborers, some were criminals in 1860, and some were local politicians (and no, I'm not going to make a cheap joke there..;).
I only found 1 thing that connected those 298 men based on the Census (some were from as far away as the Arkansas/Texas border and joined in Batesville--quite a trip in 1863 for a Unionist!).
Not one of them owned a slave according to the census. Pretty amazing, since I figured at least one of them would have--and some of them were pretty wealthy for the time (one man claimed nearly $40,000 of property value in 1860).