What did the First U. S. Congress add to the U. S. Constitution?

On September 25, 1789, after several months of debate, the first Congress of the United States adopted 12 amendments to the U.S. Constitution–the Bill of Rights–and sent them to the states for ratification.

Explanation:

I agree with u because I just learned about the 12th admendent when I was in school I hope this helps.

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.