My entire original answer: “ Because a dozen or so major cities with a majority of the nations criminals, drug users, welfare recipients, misfits and radicals would control the country. Plus the great % of sparsely populated but productive part of the country would have little say on how they are governed. The original framers of our constitution wanted a truly representative democracy where all peoples/groups/minorities would have a say in their governance. They didn’t want mob rule. PS of course i realize the mega cities have many, many decent and productive people living in them”