Entirely with the states under the Articles of Confederation.
Partly with the general government, and mostly with the states under the Framers’ constitution.
Post 17th Amendment, mostly with the general government, and in time, less and less with the states.
Increasingly within the executive department since LBJ, yet subject to congressional oversight.
Within politburos under Obama, two of which are entirely separated from free government and congressional oversight. These are the IPAB, and CFPB. The ancients would recognize this arrangement as pure tyranny.
In the future, should Leftists regain congress and the presidency, expect wholesale transfer of power to many additional star-chambers.
Article V.