Article I of the US Constitution puts this power in the hands of each State's legislature.
If you are interested in this topic, there is a fascinating development in this occurring in the Second Congressional District of Maine, which has adopted Ranked Choice Voting to determine its representatives. The loser of this year's election just sued in Federal Court to invalidate this as a way to hold an election.
A future states to the north of a set point would be free.
it was the reduction of nuclear weapons
