A clarification for today's front page. It seemed a bit jarring that Donald Trump and Hillary Clinton did not shake hands at all at the debate. So I set out to investigate if that ever happened before in a presidential debate. I watched footage from all 27 presidential debates since 1976, the first year presidential debates where held in front of a live television audience. 

In most debates, candidates shook hands before and after. Some debate footage didn't start until candidates already were in front of podiums or cut off too soon to see if they met for a handshake afterward. And there was one debate in 2008 when Barack Obama and John McCain avoided shaking hands afterward.

But through the second presidential debate of 1976, at least one handshake at each debate can be viewed in easily accessible online video (or in the case of the first presidential debate of 1980, a photograph).

So based on what I learned last night, the item about handshakes on today's front page is qualified: "At least since the second presidential debate in 1976 candidates have shaken hands before or after the debate -- and often both -- until Clinton and Trump avoided shaking hands in their final meeting."

That qualification bugs me, so I made a quick call to the Gerald R. Ford Library this morning and a helpful archivist pointed me to contact sheets of White House photographs for Sept. 23, 1976, the day of the first debate. Clearly visible in roll 1608, frame 10A is a picture of Ford and Carter shaking hands after the first debate. (Incidentally, the first debate of the modern era was a bit of a flop.)

So with help from the Gerald R. Ford Library, I can now say: until last night, there had never been a presidential debate in front of a live television audience that did not include at least one handshake before or after.