If you’ve watched any political drama from "The West Wing" to "House of Cards" to "Veep," you know that politicians have handlers. And while some jobs like Chief of Staff and Press Secretary sound familiar, there are a few political jobs that don’t get the spotlight quite as often. For example: do you know what an advance person does?

Josh King is a former Clinton White House staffer and the author of "Off Script: An Advance Man's Guide to White House Stagecraft, Campaign Spectacle, and Political Suicide." He visited Trump Tower with Kurt Andersen to examine the site where Donald Trump announced his candidacy for the presidency — and to dissect what goes into every political event behind the scenes.

Kurt Andersen: You were an advance guy, you worked in the Dukakis campaign and then in the Clinton White House — what does an advance guy do?

Josh King: Well, if you think of it in terms of how Bruce Springsteen puts on a rock concert, it’s not just The Boss walking out with his guitar. There’s a huge army of roadies, people who think through what his tour schedule is going to be, where the stage is going to be set, what the song list is going to be, all these have parallels in politics.

Coming down the escalator was kind of an unorthodox way to go, and it did look strange. He’s passive, he’s standing there with this slow-moving escalator. It looked kind of ridiculous to me — was that a bad idea?

The whole idea of a walk-in, or an entrance, is the basic ingredient of a major political event. If you think about the practical constraints here at Trump Tower, how else are you going to show the grand movement toward the stage whether you happen to be stationary on the escalator or not? So they start the soundtrack with Neil Young’s “Rockin’ in the Free World,” and they come down the escalator, and think about it: it gives about 15 seconds of camera tracking to let the correspondent say “Donald Trump announced his candidacy today at Trump Tower.” Cut to tight shot of the major sound bites they want to take for that story.

It’s interesting looking at the conventions this year. Donald Trump talked about how boring political conventions are and said “we’re going to give real show-biz pizazz to this one.” Man, judging on show-biz pizazz the Democratic convention won, right?

By a landslide. Just think of the mileage that Hillary Clinton got for weeks from the appearance of Khizr Khan and his wife. No one probably knew in advance that Mr. Khan would pull out a $1 copy of the Constitution and hold it up, but that became the enduring picture of Mr. Khan’s message. And for all the millions of dollars that were spent on construction and stagecraft, a $1 copy of the Constitution became the enduring message of the convention.