As you know our U.S. Constitution has 27 Amendments. The process of Amending the Constitution is explained in Article V of the document itself.
The 27th , and last approved Amendment, was submitted by James Madison along with what became our Bill of Rights. It’s a good one and it finally received approval of Michigan, the last needed state, on May 7, 1992. It says that Congress can’t give itself a raise unless a national vote has intervened before one can be granted. Why didn’t that pass with the other 10 Amendments of the Bill of Rights? I dunno.