When Jeb Bush's presidential campaign announcement was interrupted by immigration protesters, the crowd barely missed a beat. "Jeb! Jeb! Jeb!" they chanted. And: "We want Jeb!" And, according to The Guardian, that old standby: "U-S-A! U-S-A!"

In the event that his campaign launch was similarly interrupted, Scott Walker's staff reportedly prepped volunteers to start up the same chant. Someone starts hollering about union jobs? U-S-A! U-S-A!

There are two rhythmic patterns that make for great chants. There's the up-down-up-down pattern in "LET's go, TI-gers" (often followed by clap-clap-clapclapclap). And there's the staccato three-syllable pattern of "U-S-A!" or "Let's go Mets!" (The clapping on that one is on each syllable, usually in increasing tempo.)

But how did the elegant fervor of "U-S-A" become the go-to chant for repelling political disagreement?

In 2011, shortly after the death of Osama bin Laden and the cheering celebration outside of the White House that resulted, the Atlantic's Daniel Fromson looked at the history of the chant. While it existed for years, popping up occasionally during an Olympic competition, the chant really caught hold in 1980 during the United States' men's hockey team's improbable run for gold.

Given how utterly bananas the crowd was during the match between the U.S. and the Soviet Union -- you know, the "Miracle on Ice" one -- it's hard to hear much of anything. But in a snippet from a highlights video, you can clearly see at least one dude going through the motions. U! (mouth in a circle; clap) S! (mouth wide; clap) A! (mouth open; clap). And on and on to infinity.

That answers half of the question. To answer the other half, we looked at news reports.

Two years after the hockey team took gold, Ronald Reagan was facing his first midterm election as president. In September 1982, he headed down to Richmond (as UPI put it, "the capital of the Confederacy") to campaign for Republican candidates. Speaking before an audience of about 4,000, and with the support of a brass band, Reagan made his case -- until he was interrupted by an anti-nuclear weapons activist.

The man, a representative of the Richmond Peace Vigil, began reading a letter aloud that called for the dismantling of ''all existing nuclear weapons.''
He was immediately taken outside by guards as crowd booed him and some of the band members loudly chanted, ''U-S-A, U-S-A.''

Reagan, true to form, said he couldn't even hear what the guy was saying -- no doubt with a charming grin.

Why the chant was "U-S-A" isn't clear. In part, it was probably just easy to shout loudly. And in part, it was probably meant to show patriotic support, pitting the no-good protester against the all-American president and his audience. The extent to which that undertone persists in current usage is left as an exercise to the reader.

Whatever the reason the band used it, it stuck. And 33 years later, it offers Republican candidates a double-whammy of effectiveness. First, it drowns out the complaints. Second, it lets them once again envision themselves as Ronald Reagan.