Regarding the "1st Northeast Missouri Cavalry," there does not seem to have been any use of that particular designation during the Civil War, something Scott Sallee addressed in his 200 Blue & Gray Magazine article, "Porter's Campaign in Northeast Missouri, 1862."
Sallee speculated the term was created as an "afterthought" during the publishing and indexing process by the editors of the "Official Records of the War of the Rebellion" 20 years after the conflict was over. Over the years I have seen other writers who noticed the problem of the "1st NE Cavalry" designation but I never compiled a file on the issue to have the documentation at my fingertips since I never foresaw it arising as an issue in my own writing. But Sallee's reference is one I do have.
Anyway, this is the origin of my question regarding separating documentable wartime fact relating to Porter's Regiment from postwar-phraseology possibly arbitrarily created to fill a gap in knowledge (i.e., confabulation). And so I am wondering just how deep that postwar creative process went.