It's up to each state to determine how to send its electors (48 states use the winner-take-all format, with Maine and Nebraska using congressional districts).

It's up to each state to determine how to send its electors (48 states use the winner-take-all format, with Maine and Nebraska using congressional districts). Because of this, the NPV movement only needs enough states to make up 279 electoral votes before it can take effect; no constitutional amendment is necessary. For further reading, this Wikipedia article breaks it down pretty well: https://en.wikipedia.org/wiki/National_Popular_Vote_Interstate_Compact https://en.wikipedia.org/wiki/National_Popular_Vote_Intersta...