More than 4.2 million people have already voted early in the presidential election, vastly exceeding the pace of 2016 as Democrats amass a commanding lead in returned mail ballots.In the 2016 election, around 75,000 people had voted early at this point, across significantly fewer states that had started early voting and reporting their numbers, according to the United States Elections Project.The current national aggregation of in-person and mail-in vote totals includes more than 20 states that…