Vice President Biden took part in the pregame ceremonies, prompting tight security throughout the stadium and delaying fans trying to get in. Soccer great Walter Bahr, whose assist helped the United States beat England in the 1950 World Cup, served as honorary captain.
Oh, by the way, the Union won, 3-2, raising their record to 1-1.
Before the game, there was a solemn moment, as fans paused in silence to mark the death of Poland's president, killed in a plane crash in Russia early Saturday with 96 others.
But there were moments of exultation, too, that began much earlier, at least for some.
"It's great to have soccer back," said Brian Torrence, 32, of East Norriton, a Union season-ticket holder who once helped handle public relations for the old, indoor Philadelphia Fever. He and his buddies set up to tailgate outside the stadium at 1 p.m., five hours before game time.
Judging by the activity in the lots outside the Linc, it could have been an Eagles game, with fans cooking on grills and plucking metallic tubes of their favorite beverages from icy coolers.
But the fans were wearing blue and gold, not green, and it was the loose soccer ball that dribbled free.
Inside the stadium, children wore soccer jerseys of every color. Plainly, there had been a run on Union gear in recent weeks, as loads of fans wore team jerseys with the distinctive wide gold stripe down the front.
In the Sons of Ben supporters section, one fellow had on a kilt, two wore hockey masks painted with the Union logo, and one fan, 25-year-old Jessica Kulp of Norristown, was trying to hang on to a giant Union flag in the face of a stiff breeze.
"I just got handed it by the Sons of Ben!" she said.
Outside, before the game, Union flags flew from the backs of cars. The late evening sunshine was glorious.
"All the men in our family are going to be here today. Soccer has always been in our blood," said John Stefano, 36, of Washington Crossing, who was kicking a ball with his brother, Phil, 28, of Philadelphia.
Their Italian father raised them on the game, they said, and both were thrilled to have a new hometown team, whatever the final score.
"We'd love to see them win, but that's not what today is about," Phil Stefano said.
Added John: "Philly should have had an MLS team years ago. It's about time. Philly's going to have a huge following."
The game was the first pro soccer match played here by a hometown, major-league team in 30 years. It was 1980 when the Philadelphia Fury moved north and became the Montreal Manic.
At game time, 6:10, Union officials said, they had sold 32,000 tickets, with walk-up sales uncounted. That's a big crowd anywhere, anytime for Major League Soccer. And it was miles beyond what the Fury, and before them the Atoms, drew in the old North American Soccer League.
The Union will play their first two home games at the Linc while PPL Park is completed. The second game, set for May 15 against FC Dallas, is likely to be a better test of attendance, lacking the event status that surrounds a new club's inaugural home game.
The first game at PPL Park is scheduled for June 27, versus the Seattle Sounders.
Since the departure of the Fury, fans have seen international exhibition games, indoor teams, women's teams, and minor-league clubs. But they hadn't had a pro men's team to root for.
In their third and final year, the Fury drew a paltry average of 4,778 fans. The Union have sold more than 11,100 season tickets and plan to cap sales at 12,000.
Saturday night, ticket booths did a steady business as game time approached.
"Soccer for me is special in my life," said Carlos Miranda, wearing the white-and-blue jersey of Argentina. "I grew up playing in my country since I was 2. Soccer is our life, our passion."
He showed off four tickets - he was accompanied by his wife, Cecilia, and their children, Valesca, 6, and Jordan, 3, all of them excited to be seeing the game.
"I've been planning this for weeks," Miranda said.
Sakiewicz, the team's chief executive officer, welcomed fans to the game. It was he who, three years ago, trudged across a muddy Delaware River waterfront, insisting to all who would listen that a stadium could be built, a team could rise, and both could be successful.
"It feels great, a lot of emotion," he said Saturday night. "At the same time, this is the start of a very long journey."
Contact staff writer Jeff Gammage at 215-854-2415 or firstname.lastname@example.org.