Why is the electoral college considered "51 separate elections" instead of one national election?

Because each person does not actually vote for a president. When we vote for a candidate we are actually voting for a group of electors, to elect our president off of each states popular vote excluding Maine which does proportional voting.

Explanation:

Let's say you live in Kansas and electoral votes are based off of number of Congressmen/women which totals 6 2 senators and 4 reps which equals 6 electoral votes. A person voting in this state is voting either for 6 republican electors or democratic electors. When you vote for a candidate if that state goes republican those 6 GOP electors vote for the nominee that the state won. Washington D.C gets three electors even though it is not a state. So each state holds a separate elections since we all are voting for electors of the party you vote for. As well as D.C which that right was given to them in the 70s.

the right answer is the end of world war ii

after the end of a global wwii all the nations involved, in an attempt to create an organization to maintain world peace. this agreement would work settling international disputes via negotiation and arbitration instead of leading the issues escalate to another war.