The best part of a surprise party is the surprise.

Though Gabby Thomas wasn’t exactly surprised when she entered the after-party following her gold medal in the 200 meters Tuesday night, the hundred-plus family and friends in attendance at the New Balance hospitality house in Paris treated it just like a surprise party.

“She just walked in and the place erupted,” said Martha McCullagh, Thomas’ track coach at Williston Northampton School, who was in the stands for the race and in attendance Tuesday night.

Aunts, uncles, cousins, Williston friends, Harvard friends, and friends of friends attended the party, a celebration of Thomas’ first career gold medal and the first American gold in the 200 since it was won by Allyson Felix, a childhood idol of hers. The party lasted a few hours and was full of “lots of hugs, lots of pictures, lots more hugs, a few tears, lots of laughs,” McCullagh said.

On Wednesday, Northampton Mayor Gina-Louise Sciarra proclaimed Aug. 6, 2024 “Gabby Thomas Day.”

“The City of Northampton exuberantly commemorates Gabby’s victory and we express our profound joy to have been part of her incredible journey,” Sciarra said in the proclamation.

Thomas entered Tuesday’s race as the defending bronze medalist, No. 1 qualifier and favorite for gold, and she did not disappoint. She took the lead on the turn and pulled away even more on the home straightaway to cruise to victory in 21.83 seconds. While the five runners following Thomas were separated by just 0.16 seconds, Thomas cruised past silver medal winner Julien Alfred by 0.25 seconds.

“It was the same kind of dominance that we saw in high school, although for the high school meets, it was that but way more,” McCullagh said. “Now she’s running against the best in the world. You wouldn’t expect your high school athlete that dominated everything, when you get to the world stage, would still be dominant.”

Thomas, now 27, won 12 New England titles at Williston and holds school records in the 100, 200, 4x100 relay, long jump and triple jump. She also excelled in cross country, basketball and soccer. Though she now lives in Austin, Texas, many of her connections to Hampshire County have intently followed her career, and Williston hosted a watch party for her race Tuesday.

For McCullagh, it’s hard to believe the girl she met in Algebra II as a freshman at Williston is now an Olympic champion. She said she’s been pinching herself constantly since the race.

“She’s an incredibly talented, experienced, qualified professional athlete,” McCullagh said. “But at the same time, she’s a kid I’ve known since she was 14.”

McCullagh sat about 15 rows back from the front row at the end of the straightaway of the Stade de France track and said she had a great view of Thomas’ turn and finish. She bolted for the rail as soon as Thomas crossed the finish line, and Thomas came over to give her a hug in between receiving her American flag and ringing the bell of the Stade de France, which has become a tradition for each track and field gold medalist at the Paris Olympics.

“It was still so raw for all of us,” McCullagh said. “Because she had just gotten wrapped in this flag.”

Unlike in Tokyo, when Thomas won bronze in front of a stadium filled with cardboard cutouts, the Stade de France was booming with 80,000 fans and a light show. At a lunch with family and friends following her qualifying heat on Sunday, Thomas remarked that on the track, the steepness of the stands in the Stade de France makes it feel like “everybody is right on top of you.”

Alongside those 80,000 roaring fans, Thomas’ family and friends, who were unable to attend in 2021, were right there with her. The NBC broadcast showed Thomas’ mother, Jennifer Randall, a former UMass professor, crying after Thomas’ win and showed the mother-daughter pair hugging at the rail after Thomas picked up her American flag.

“I have never experienced anything like this,” Thomas said on the NBC broadcast after the race. “This is the happiest moment of my life. All of my friends and family are here, from every stage of my life. Tokyo, I thought it was great, but it did not compare to this. This is incredible. It’s a moment I’m going to remember forever.”

Thomas wasn’t the only emotional one. After McCullagh got back to her seat, she began crying. A Hungarian photographer asked her about her connection to Thomas, and when McCullagh told him she was Thomas’ high school coach, he said he’d be “honored” to give her his pictures. They met up at the Stade de France on Wednesday night.

Thomas doesn’t have family living in Hampshire County anymore — Randall moved from UMass to the University of Michigan in 2022 — so it is yet to be determined whether Northampton will hold a homecoming celebration. Her most recent Hampshire County public appearance was in 2022, when she was the commencement speaker at Williston’s graduation. Those connected to her at Williston hope she returns for her 10-year reunion at Williston next year.

After the Tokyo Olympics, the mother of an Easthampton kindergartner messaged McCullagh on Facebook that her daughter’s class was holding a “heroes day,” and she was planning on dressing up as Thomas. McCullagh relayed the message to Thomas, and Thomas reached out to the young girl.

After the Paris Olympics, heroes days might have a few more Thomas costumes.