DaVon Harris, 11, of the District, sports a monster face-painting at the National Zoo on Monday. (Katherine Frey/The Washington Post)

Down the main National Zoo walkway, past the Panda Plaza and near the Elephant Trails, Jermaine and Daena Lassiter, pushing their 6-month-old daughter in a stroller, suddenly stopped their brisk animal tour underneath a small white tent.

On display there were black-and-white photos taken decades ago at the zoo on Easter Monday.

Jermaine, a federal government accountant, peered, transfixed, at a photo of a woman in a dress, holding a little boy’s hand, walking on what appeared to be the very same path.

“I like that the zoo found these pictures and blew them up,” he said to his wife.

“They’re all so dressed up!” Daena said, chuckling.

“I just like how the zoo is not trying to gloss over” the history of this day at the zoo, Jermaine said.

The zoo called the festivities “Easter Monday: An African American Family Tradition” and said the origins dated back to 1891. What caused African American families to flock to the zoo on the day after Easter isn’t known, although it seems clearly related to Washington’s segregation at the time.

One theory zoo officials have offered is that African Americans went to the zoo because they were barred from the White House Easter Egg Roll. Another holds that many black housekeepers had to work on Easter Sunday, so they used their day off on the Monday after Easter to celebrate at the zoo.

Whatever the cause, hundreds of visitors, many of them African Americans, streamed into the zoo Monday. They hunted for eggs, sized up elephants and played animal trivia games with a wise-cracking DJ from WPGC 95.5, a hip-hop station.

Many members of black families said they weren’t sure about the event’s origins, but they knew that the event has been a central part of their lives for generations. A glance down the zoo’s main walkway showed scores of families pushing strollers, many multi-generational — grandparents, parents and kids.

Catherine Fitch, 52, a nurse from the District, watched after her granddaughter near the egg hunt while a band played “The Hokey Pokey.” Her daughter, niece and other relatives were scattered around the zoo, but she luxuriated in the time alone with her granddaughter.

“This feels more like a family reunion, as opposed to a few years ago, when they had that shooting, or was it a stabbing?” Fitch said.

In 2011, a 16-year-old Southeast Washington boy stabbed a 14-year-old. More than a decade earlier, in 2000, a teenager shot and wounded seven people at the entrance. But the vibe couldn’t have been more different on Monday.

“I like it more now because you get all mixes of races together,” Fitch said. “When I was coming as a kid, it wasn’t as mixed.”

Near the zoo’s entrance, Denise Swan, 43, was pushing her granddaughter. Swan took pride in pointing out all the relatives surrounding her: “My mother. My sister. My niece. A nephew. Two great-nephews. One granddaughter. One grandson. One daughter,” she said.

“Was it 43 years ago we were here as kids?” she asked her sister, Cerona Swan. Cerona nodded.

“There were more animals back then,” Denise said.

“It was our grandmother who first started bringing us,” Cerona said, smiling. “Different schools performed. They had clowns.”

Closer to the Elephant Trails, Brittany Bridges, 19, showed up with her 10-month-old son and her aunt, Rayshone Bridges, 44. They remembered always going as a family, but they didn’t really know about the event’s historical importance.

Brittany recalled the familiar rhythms of her childhood around this time of the year. It was always church on Sunday, the zoo on Monday. And they always began Easter Monday with an egg hunt in a grassy patch near the zoo’s parking lot.

Rayshone said she thought the moment felt surreal because she could so easily remember celebrating this tradition when Brittany was a child.

“Her favorite was going to the ape house,” Rayshone said.

Brittany laughed. That’s still her favorite place now, she said.