By 6:30 a.m., runners were already at the starting line on the Parkway at 22d Street, stretching and jogging.
Some would do the half marathon, following the route to the Delaware River waterfront, then out to the zoo, peeling off in front of the Art Museum to finish along the Parkway. The rest would run the full 26.2 miles, continuing out Kelly Drive into Manayunk and back.
They were first-timers and regulars, people who ran simply for fun, and elite athletes.
Here was Capt. James Henry, 28, a physician at the Walter Reed Army Medical Center in Washington, who three years ago ran a marathon for a sergeant who died in Afghanistan. Now, he knows "myriad" more.
American soldiers in Germany, many awaiting deployment to battlefronts, chanted the countdown in a recorded performance. "Three . . . two . . . one," and, as the obligatory theme from Rocky played, the first wave of runners shot off toward City Hall.
In a few minutes, another wave followed. And more after that.
Each time, most of the runners took off outer sweatshirts or pants and draped them on the fence or left them on the ground.
Madeline Resnic, 12, was right behind them. For three years, she and other family members and friends have been collecting the discards and donating them to homeless shelters through the Philadelphia charity they founded, Clothes-Pin.
It wasn't even 7:15 a.m., and Madeline and friends were already out of bags. "Just pile them up," her father, Michael Resnic, told everyone.
They collected more than 12,000 articles of clothing Sunday, and Michael Resnic said that by the end of the day, the goods would be delivered to Our Brother's Place, a shelter at Ninth and Hamilton Streets.
At 7:33 a.m., the first runners pounded past the intersection of 22d and Chestnut Streets, a designated "cheer zone" along the course.
For several blocks, hundreds of people lined the course, cheering, blowing horns, and ringing bells.
Margaret Jones of Philadelphia added a few visuals - a purple tutu, pink wings, and a boa. She was part of the crew cheering on the 153 runners who were raising more than $360,000 for the Leukemia and Lymphoma Society, one of many charities that benefited from the race.
Eric Wiessmann, 37, of Philadelphia, was waiting for the first appearance of the 150 youths in the Student Run Philly Style program. It provides running shoes and training to "give underprivileged kids the reason they need to do something spectacular," he said.
At 8:04 a.m., at 22d Street and Park Towne Place, a few members of the Philadelphia Fire Department's special-event team were mounting up. About 40 of them were on bicycles and Segways, strategically located throughout the course, and already five injuries - falls and dislocations - had been tended to, paramedic Raphael Mallard said.
A call came over his radio. An eye injury at 34th and Chestnut. "That's six," he said. With hours still to go.
By 8:10, runners in the half-marathon were beginning to stream across the finish line.
Waiting just beyond were dozens of volunteers who handed out plastic "heat sheets" to warm the runners and offered cups of water. Over the course of the day, they provided more than 27,000 gallons.
Out on the course - near the Rocky statue at the base of the Art Museum steps - Justin Spies, 34, of Conshohocken, was keeping watch for his girlfriend, Holly Ramsey, 27, a special-education teacher at White Hall Elementary School in Norristown.
This was her fourth marathon. He planned to greet her at the finish line with a dozen red roses.
Ben McGrath of Doylestown knew only one runner - his father - but he shared his enthusiasm with all. "It was all for this, Morgan," he called out, reading the name on one runner's bib.
And "Come on, Brett."
And "Dean, Dean, it's all you now!"
Soon enough, endocrinologist Glenn McGrath, 57, came into sight. "Come on, Dad!" McGrath called to him. "You're the greatest!"
By 9 a.m., the announcer warned officials to "get ready to crank up the Rocky music." He'd gotten word that the first of the full marathoners were approaching.
It got busy after that - half-marathoners streaming across, full marathoners churning parallel to them down the last hundred yards.
Mayor Nutter stood at the side, giving finishers high-fives.
Two women fell into each other's arms. "I think I'm going to puke," one said and laughed. "Awesome job," the other answered.
Many hugged. A few cried. They were breathless, pained, jubilant.
The crowd cheered as Pitcairn waited for Pellani's answer.
They've been dating for three years - he goes to Michigan State and she goes to Oakland University in southeast Michigan - and the instant she saw him get on his knee, she knew.
And yes, she would. Of course she would.
Hand in hand, they crossed the finish line.
Contact staff writer Sandy Bauers at 215-854-5147 or email@example.com. Visit her blog at http://go.philly.com/greenspace