There are very few Americans alive today who can remember the last time that the secretary at a national convention called the roll and no one won on the first ballot. It happened to the Republicans in 1948 when they took three ballots to nominate Thomas Dewey (who lost to President Harry Truman) and in happened to the Democrats in 1952 when they took three ballots to nominate Adlai Stevenson (who lost to Dwight D. Eisenhower.) 

But just because it hasn’t happened in a long time doesn’t mean that it can’t happen. If there was ever a year for it—2016 is it.

The reason we haven’t seen a brokered convention in more than half a century is that these days the voters in the primaries and caucuses usually manage to have awarded someone the most delegates before the conventions meet. As that happens, the other candidates drop out leaving the party with one nominee. Thus when the actual delegates are chosen and go to the convention, they don silly hats and cheer for the television cameras and, off-camera, they plan to turn out the vote in November and conduct their own state and local party business.