This may be an elementary question, and I apologize if that is the case.
In existing sections of the Constitution (Article I Section 2 Cl. 2; Section 3 Cl. 3; Qualification of Senators/Representatives, et c.) as originally ratified, the language “a citizen of the united States” would appear to me to clearly reflect the proper understanding people had of the structure of governement established. In my mind, there’s no question this simply refers to a free person who is at that time a citizen of any one of the States so united.
In the opening language of the 14th Amendment, if read and applied verbatim would seem to imply that there is a distinction to be made between being a citizen of a State and also a citizen of the United States. As if the two, while they would often coincide, could conceivably exist separately. (Washington D.C. is an obvious example here, but it is out of context for the question I’m asking) I assume this is the supposed justification for a lot of the “dual sovereignty” arguments litigators seem to enjoy so much. Based on the language itself, I could easily see more designing men attempting to establish the concept of a “United States” government that somehow stands in parity with the State governments that created it. Is there any evidence that this was intended by the actual framers of the amendment, given that the 14th was meant to codify the Civil Rights Act post war?