Thousands gather in New York to protest the ruling.

Nearby, sitting in a tree above the crowd, Kate Coiro, 23 held a sign that read, “You can’t be pro-gun and pro-life,” in reference to a Supreme Court decision the day before that struck down a restrictive New York gun control law.

“This was the first time I personally felt attacked by a government decision,” said Ms. Coiro, of Williamsburg, Brooklyn. “I want people to know that no one likes abortion, including people who get it. It’s no one’s plan A. But if you’re not in a place to raise a child you shouldn’t have to.”

By the evening, the crowds in the park began to disperse, and a few hundred made their way south toward Lower Manhattan, stopping traffic and eliciting cheers from outdoor diners who snapped photos.

As the march wound down in Foley Square, Maya Vargas worried about her family in Florida, one of several states with so-called trigger laws, which allow for the swift ban of nearly all abortions now that Roe v. Wade has been overturned.

“I worried a lot for my family because they live in the South,” said Ms. Vargas, 21, of Astoria, Queens. “We’re relatively privileged here in New York, we don’t have to really worry about that at the moment.”

“My younger cousins are scared,” she added.

Back at the corner of West Fourth Street and LaGuardia Place, Sophie Apple, 26, of Harlem, wondered what she could to do help those in other states.

“In some way my goal is to help supply donations where I can, volunteer where I can, help women travel to New York or other states,” she said, “because that appears to be the way forward.”

Hurubie Meko and Julianne McShane contributed reporting.