More than 33,000 people took part in the race, officials said.
In Central Park, some runners were still crossing the crossing the finish line late Sunday afternoon.
Many told CBS2's Kiran Dhillon while the race was a challenge, completing it is an emotional and rewarding experienced.
A sense of joy mixed with relief could be seen on many of the runners' faces as they crossed the finish line on Sunday.
"Exhausted!" one runner said, adding, "She was with me every step of the way! She got me through it."
"Oh my God, I feel great. It's amazing to have this done," another runner said.
The race, in its 50th year, as always drew big crowds, as well as participants from 140 countries.
PHOTO GALLERY: 2021 New York City Marathon
One New Yorker ran his 60th marathon to celebrate his 60th birthday.
"Just to get back out with COVID and travel and be involved with people again and spread some goodwill and energy, it's important," Ron Romano said.
A pair of New York City sisters, both dermatologists, ran together, pushing each other every step of the way.
"We run through holding hands," Dr. Liz Hale said.
"Each time one of us pulls the other through," Dr. Julie Karen added.
Along the race route, families and friends showed up to support their loved ones at mile 16, all while tracking their whereabouts on an app.
One group came to support first-time runner Eric DeMartino of New Jersey.
"Every single day the kid works out, wants to do this. That's a warrior and I'm glad I got to be here to see him do this," DeMartino's roommate said.
And three little ones, along with their mom, came from New Hampshire to cheer on dad Omar.
"We're excited to come support him and we're so proud of him," Jen Brahim said.
The marathon has only been canceled twice in its five-decade history -- once because of Superstorm Sandy and last year because of COVID.
Many runners told Dhillon that's why this year's race had special meaning, with some dedicating their run to the lives lost during the pandemic.
"New York is back and they are back in numbers," one runner said.
Racers added it was the support from the crowd that helped push them past the finish line.
"It was such a great race, the crowd pumped us up the entire time. I couldn't have done it if it wasn't for the crowd," one runner said.
"It was hard, but it was beautiful weather. The people were cheering. I kept giving people high fives and they kept me going. The crowd was electric. New York City, baby," another said.
Runners said they were thrilled to participate in the iconic event, especially on the 50th anniversary.
Most said the first thing they planned to do after the run was take a nap and have a big meal.
CBS2's Natalie Duddridge contributed to this report.
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