Though organized by the Obama campaign in just a few days, the concert, at 20th and the Parkway, drew an estimated 50,000 people. According to Obama staff, it also added 21,000 new ground troops to the Illinois senator's campaign effort in must-win Pennsylvania.
The Democratic presidential candidate's potent ground operation was on display up and down the Parkway, with volunteers at almost every turn collecting personal information about concertgoers and doling out voter-registration forms.
The goal was to increase registration in the state by tomorrow's deadline while luring new volunteers as the campaign enters what Gov. Rendell said yesterday would be a "meaner," "tougher" and "dirtier" final few weeks against Republican John McCain.
Springsteen was scheduled to hold similar shows today in Ohio and tomorrow in Michigan - two other critical states in the Nov. 4 election.
The Parkway crowd was a largely captive audience of Springsteen and Obama fans, most of whom had been required to register with the campaign online or on site to enter gated viewing areas.
Some McCain supporters also were in force to see the much-adored rocker from the Jersey Shore. They watched from peripheral areas where registration was not required but, in some cases, provided a better view.
Rendell made a strong appeal for undecided voters to swing toward Obama. His full-throated pleas were carried over two large video screens that lined the Parkway.
But first the governor took a jab at GOP vice presidential nominee Sarah Palin and her demeanor at last week's debate with Obama's running mate, Delaware Sen. Joseph R. Biden Jr.
"I promise you that as long as I'm up here I will not wink at you," said Rendell, a former national Democratic Party chairman.
He urged supporters to go door to door to win over neighbors. He implored Pennsylvania college students to register to vote with campus addresses instead of logging their votes out of state, if that was where their parents lived.
"We may very well need it here in Pennsylvania," Rendell said.
Hours before the rally, Obama's vaunted operation organized and reorganized itself and its foot soldiers in a hierarchical flow chart.
Volunteers were advised to "be friendly, but also be aggressive."
The quest was "data," said an Obama staffer: e-mail addresses and phone numbers from concertgoers. Thousands had given their information online to get a general-admission ticket. Volunteers collected tickets in trash bags at the gates.
Staffers continued to press for personal information before letting people pass through to the central viewing area.
Many showed up early to volunteer at the event, some diligently listening to training sessions, others snagging a close-up view, others questioning the volunteers who snagged close-up views.
"This organization is ridiculous," said Michael Dempsey, 18, a Dickinson College student. "They told us to yell at these other volunteers. It's hilarious."
Kimeka Campbell, an Obama worker, addressed the crowd before Springsteen and instructed people to text-message the campaign. Those numbers will then be hit up again for fund-raising and volunteer efforts.
Although the major intent of the rally was to register voters, Dawn Trunfio, 28, an Obama volunteer, said she had only found 10 people who needed the forms. "Most are already registered," she said.
Springsteen was the clear draw, despite unfounded rumors that Obama might make a surprise appearance.
Playing on a small stage with only a harmonica and a guitar but thundering loudspeakers dangling from cranes on either side of him, Springsteen opened with his song "Promised Land" and ended it 40 minutes later with a version of Woody Guthrie's "This Land Is Your Land."
"I'm not Barack Obama," Springsteen said as he came onstage in sunglasses and blue jeans, "but I'll do my best."
He strummed rhythmically as late-afternoon sunlight sparkled off his sunglasses and guitar strings. Thousands stood entranced, happily jammed between trees whose leaves had begun to change color. City Hall's tower, ivory white since it was blasted clean a few years ago, was aglow in sunlight, serving as Springsteen's backdrop six blocks away.
In the thick of the masses, Daniel Pearlman, a 45-year-old real estate lawyer from Chicago, played air guitar and sang along with "Thunder Road" - which he declared, loudly, to be the "greatest song ever written."
From Pearlman's disadvantaged vantage point, Springsteen appeared to be a plaid dot, smaller than the backward Covenant House baseball cap on the head of a guy a few bodies closer to the stage.
The music, however, reached Pearlman with full, transporting effect as he threw his head back and sang along: "It's a town for losers, we're pulling out of here to win!"
As his set progressed, Springsteen dialed back the music and amped up the political commentary, saying the nation was like a house that had fallen into disrepair, but that Obama could help rebuild.
"I don't know about you, but I want my house back. I want my America back, and I want my country back," Springsteen said before playing a song inspired by 9/11, "The Rising."
Some in the crowd had rolled the dice on Obama's showing up. It was a twist on the Springsteen-fan ritual of going to the Stone Pony in Asbury Park, N.J., for a show and hoping the Boss might make a surprise appearance, as he sometimes does.
"We were hoping to see the man . . . Obama," said Abigail Milder, who biked over from South Philly with her husband and daughter. "We were hoping for the big intro."
Cindy Warkow, 46, of Dresher, sold her three daughters on the event by holding out hope of an Obama surprise. "They're like, 'Who's Springsteen?' "
A review of the music.
Contact staff writer Maria Panaritis
at 215-854-2431 or firstname.lastname@example.org.
Inquirer columnist Dan Rubin contributed to this article.