Outside of show business, the presidency is one of the few jobs that comes with its own song.

In a tradition dating back to the 1800s, when the commander in chief enters the room, the U.S. Marine Band strikes up "Hail to the Chief."

It starts with the so-called "Ruffles and Flourishes" — four of them in succession. Then the song itself. A slow, melodic, instantly recognizable march — entrance music for the leader of the free world.

The first time presidents hear "Hail to the Chief" played for them is right after taking the oath of office. There are no firm rules for when — or how often — to use the song.

In these early days of the Trump administration, we haven't heard it much. He used it during a visit to a Boeing plant in South Carolina, but President Trump is just as likely to opt for the music featured at his campaign rallies, including the ultra-patriotic country ballad "God Bless the USA" by Lee Greenwood. That's what he used recently at the big Conservative Political Action Conference. It's less stately, but a crowd-pleaser — and easier to sing along to.

The real tradition of "Hail to the Chief" goes back to President James K. Polk, elected in 1844. It grew out of the practical, political instincts of first lady Sarah Childress Polk.

"Polk was not an over-the-top character; he wasn't larger than life," according to Thomas Price, curator of the James K. Polk Home and Museum in Columbia, Tenn. "Sarah Polk mentioned that on occasion he would enter crowded rooms unnoticed."

Polk was not a dashing military figure like some of his predecessors. He wasn't good at oratory or comfortable socializing. Price says the first lady recognized all of that as a potential problem for her husband.

But, with a keen sense of how Washington worked, she had an idea.

"Wanting to bring some fanfare to the presidency, she had 'The President's Own' Marine Band play the song 'Hail to the Chief,' " curator Price says, so that people would know the president had arrived.

From there it went on to become the president's official anthem.

Before Polk, the song — adapted in (or around) 1812 from an old Scottish tune, by orchestral conductor James Sanderson — had been played for earlier presidents, but not routinely.

Still, the song's use is subject to the wishes of any occupant of the White House. Some have despised it. President Chester Arthur even launched what today might be called a "Repeal and Replace" campaign against the song. He stopped using it, enlisting none other than John Philip Sousa to compose a new presidential theme song. The fact that you've probably never heard (or heard of) Sousa's "Presidential Polonaise" tells you how successful that effort was.

Now it's Trump's turn to decide how prominent "Hail to the Chief" is on his presidential playlist.

And, in case you were wondering — or hoping to sing along yourself — the song does have rarely heard lyrics, written sometime in the 1900s by Albert Gamse:

Hail to the Chief we have chosen for the nation,

Hail to the Chief! We salute him, one and all.

Hail to the Chief, as we pledge cooperation

In proud fulfillment of a great, noble call.

Yours is the aim to make this grand country grander,

This you will do, that's our strong, firm belief.

Hail to the one we selected as commander,

Hail to the President! Hail to the Chief!

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