No matter what nonsense occurs for the next 18 days of the presidential election, it makes no difference for at least 4 million Americans, since they've already voted. If Donald Trump's poll numbers plunge through the basement floor or if Hillary Clinton suddenly stumbles: No matter. For these happy citizens, they don't have to care one iota, save for some potential buyer's remorse. Those 4 million people, a number making up 3.1 percent of the total vote in 2012, are free.
Most of them voted during a period when Hillary Clinton had a national lead -- a narrow lead, if they voted a few weeks ago or a large lead if they voted more recently. So while it's probably not a surprise that early vote tallies in several swing states show a shift to the Democrats since 2012, it still means that Clinton has a greater percentage of banked votes than President Obama did at this point four years ago.
Catalist, a voter data firm that works mostly with Democratic campaigns, provided The Post with early vote numbers from several battleground states that allowed us to compare current returns with the number of ballots returned in years past. In seven states for which returned ballot data was available by party, Democratic ballots made up a larger percentage of what had come back by the 20-day mark (that is, by 20 days before Election Day) than in 2012 (or in 2008 for Florida). In some cases, like Arizona and North Carolina, the shift to the Democrats was substantial.