The Constitution both implicitly and explicitly makes state sovereignty fundamental: implicit in the separation of powers, the establishment of the Senate and the Electoral College; explicit both in Article 4, Section 4--which guarantees republican state government (and which was a force for national unity)--and in the10th Amendment. The 10th Amendment, the coda of the Bill of Rights, verbatim:
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."
In other words, the national government, that thing called the United States Government, is the creation of the states, and has been given specific, and limited powers by the states and is therefore not superior to them except in its specified powers.