Above all, the electoral college had nothing to do with slavery. Some historians have branded the electoral college this way because each states electoral votes are based on that whole Number of Senators and Representatives from each State, and in 1787 the number of those representatives was calculated on the basis of the infamous 3/5ths clause. But the electoral college merely reflected the numbers, not any bias about slavery (and in any case, the 3/5ths clause was not quite as proslavery a compromise as it seems, since Southern slaveholders wanted their slaves counted as 5/5ths for determining representation in Congress, and had to settle for a whittled-down fraction). As much as the abolitionists before the Civil War liked to talk about the proslavery Constitution, this was more of a rhetorical posture than a serious historical argument. And the simple fact remains, from the record of the Constitutional Conventions proceedings (James Madisons famous Notes), that the discussions of the electoral college and the method of electing a president never occur in the context of any of the conventions two climactic debates over slavery.
If anything, it was the electoral college that made it possible to end slavery, since Abraham Lincoln earned only 39 percent of the popular vote in the election of 1860, but won a crushing victory in the electoral college. This, in large measure, was why Southern slaveholders stampeded to secession in 1860-61. They could do the numbers as well as anyone, and realized that the electoral college would only produce more anti-slavery Northern presidents.
Yet, even on those terms, it is hard for Americans to escape the uncomfortable sense that, by inserting an extra layer of electors between the people and the president, the electoral college is something less than democratic. But even if we are a democratic nation, that is not all we are. The Constitution also makes us a federal union, and the electoral college is pre-eminently both the symbol and a practical implementation of that federalism.
The states of the union existed before the Constitution, and in a practical sense, existed long before the revolution. Nothing guaranteed that, in 1776, the states would all act together, and nothing that guaranteed that after the Revolution they might not go their separate and quarrelsome ways, much like the German states of the 18th century or the South American republics in the 19th century. The genius of the Constitutional Convention was its ability to entice the American states into a more perfect union. But it was still a union of states, and we probably wouldnt have had a constitution or a country at all unless the route we took was federalism.
Source Washington post
https://www.google.com/amp/s/www.washingtonpost.com/amphtml/posteverything/wp/2016/11/15/in-defense-of-the-electoral-college/