As many as 100 million people are expected to tune in for tonight's first presidential debate between Donald Trump and Hillary Clinton.
But what, if anything, will they take away from the event?
Here & Now's Peter O'Dowd talks with Derek Thompson of The Atlantic about research into how much debates actually affect a voter's choice of candidate.
Here's a video of one presidential debate that some voters said did make a difference:
This segment aired on September 26, 2016.