Based on a binomial distribution - which assumes that all polls are independent of one another, which theoretically they should be - it's realllllllllllllly unlikely. Specifically, the odds are 1 in 9.5 trillion against at least this many polls showing such a close margin.

This is a clear-as-day example of what we call herding: the tendency of some polling firms to move with the flock by file-drawering (not publishing) results that don't match the consensus or torturing their turnout models until they do.

In this election, the incentives are doubly bad, because the polling averages in the swing states are close to zero - so a pollster can both herd toward the consensus and avoid taking a stand that there's a ~50/50 chance they'll later be criticized for by publishing a steady stream of Harris +1s, Trump +1s and ties. Lately, a lot of national polls have also shown near-ties after usually showing Harris leads earlier in the race. We wonder if there's been an increasing amount of herding there too, perhaps involving the use and abuse of likely voter models - national polls have tightened and moved toward Trump considerably more than state polls have become Trumpier over the past month, except in Nevada and Florida.

All of this herding - and hedging - increases my concern about another systematic polling error. It might be an error in Trump's favor again, but it won't necessarily be: pollsters may be terrified of showing Harris leads after two cycles of missing low on Trump, and they probably won't be criticized too much for a Harris +1 or even a Trump +1 if she wins in Michigan by, say, 3 or 4 points.

In 60 or so hours, none of this will matter anymore except as ground for forensic examinations of the pollsters based on the accuracy - or lack thereof - of their work.

It's up to us, the voters to show up - if you haven't already voted - and make your individual voice heard amongst the tens upon tens of millions of fellow Americans in deciding the type of future you want this nation to have and particularly whom you want to see representing us as elected representatives for the next 2/4/6 years. VOTE!

If people really want to understand why things are what they are 24 hours from Election Day, this is the best explanation from someone who certainly knows.

One of the reasons Saturday's Selzer poll out of Iowa was so earth-shattering is that she is a pollster that doesn't need to make adjustments on her modeling from previous elections because for the most part she got it right when other pollsters didn't, picking up trends, electoral dynamics and composition that matched the voting electorate in Iowa.