One reason fans keep flocking to Bruce Springsteen shows — including Friday’s sold-out show at Nationals Park — is that an element of surprise exists from night to night, a rarity when it comes to arena-size concerts, where what people pay for is less a music event than a carefully choreographed production. Most acts play the same songs in the same order, and have the same pyrotechnic explosion at the same moment every night.

A Springsteen show is different. There are scripted moments, of course, but on any given night, he could break out a song he hasn’t played in years. To give you some idea of what the Boss might play at Nationals Park on Friday, we’ve put the setlist possibilities into categories and included a handy pie chart.

DisclaimerThis is a non-scientific user poll. Results are not statistically valid and cannot be assumed to reflect the views of Washington Post users as a group or the general population.

The wild cards — 28%

For true Springsteen fanatics, this is where things get fun. Will he dig deep for “Atlantic City”? Maybe he’ll take it back to the beginning with “The E Street Shuffle” or break out “Prove It All Night.” Perhaps a fan with a colorful sign request will catch his eye and the audience will be treated to a real rarity. “In the past several years, Springsteen has been taking requests from the crowd. He has never been stumped,” David Remnick wrote in a recent New Yorker profile. Springsteen usually will play a cover or two as well. You’ll likely hear more obscurities in cities where Springsteen plays multiple nights; in single-show cities such as Washington, the “standard” setlist usually is the norm.

The almost certainties — 24%

These songs aren’t locks on the level of “Born to Run,” but it’s likely that on most nights you’ll hear many of them. Of such tried-and-true favorites as “Badlands,” “Rosalita,” “Glory Days,” “Hungry Heart,” “Working on the Highway,” “Darkness on the Edge of Town” and “Darlington County,” one of them might not make the cut, but you can count on such classics making up about a quarter of the set.

New material — 20%

Springsteen released his 17th studio album, “Wrecking Ball,” in March, and his spring tour featured it heavily. At his Verizon Center performance in April, he played eight of the album’s 11 songs. This second trip across the country is still technically part of the Wrecking Ball tour, but don’t expect to hear almost the entire album; five new songs (likely including the album’s title track) looks to be the norm this time around.

The every-night classics — 16%

It’s great when Bruce breaks out the rarities, but there are certain inalienable rights that come with buying a Springsteen ticket. Hearing “Born to Run” is one of those rights. There’s a 99 percent chance you’ll hear a handful of other songs at Nats Park, particularly during the encore: “Tenth Avenue Freeze-Out,” “Thunder Road” and “Dancing in the Dark.”

“The Rising” staples — 12%

The Boss experienced yet another resurgence in popularity with the release of his 2002 album, “The Rising,” which became the unofficial soundtrack to American resilience post-Sept. 11. Three of the album’s best songs, the title track, “My City of Ruins” and “Waitin’ on a Sunny Day,” are setlist regulars.