A diverse group of 69 swimmers held hands Saturday as they floated in Lake Michigan off the shore of 31st Street Beach in remembrance of one of the city’s darkest moments — the deadly race riots of 1919.

Near the same spot on a warm and sunny afternoon exactly 100 years earlier, a 24-year-old white man began throwing stones at a group of black boys whose only crime was inadvertently crossing an imaginary line in the water that separated white and black swimming areas at what was then 29th Street Beach.

When black 17-year-old Eugene Williams fell into the water and drowned, his death became a flashpoint for the riots, which left dozens killed and hundreds injured before they were quelled.

“This history isn’t something that’s discussed in your typical history books,” Jordan Rome, who took part in the event, said. “It’s important to have these conversations because that hidden history is extremely intentional.”

The show of unity at the beach, organized by two artists who have toured the country commemorating the riots, was one of several events around the city Saturday to examine and reflect on their legacy.

“I think an argument can be made that what happened here in 1919 at the beach and in the week that followed is just as impactful in shaping Chicago as the Chicago Fire was, where you get a completely different city with and without the event happening,” according to Lee Bey, a photographer, author and journalist who formerly worked as the Chicago Sun-Times’ architecture critic.

Bey and others, including Ald. Pat Dowell (3rd), spoke about the riots and their impact at an event Saturday at the Illinois Institute of Technology in Bronzeville, which featured a 30-minute lesson on Chicago history leading up to the riots.

While similar outbreaks of bloody violence occurred across the country in what became known as The Red Summer, Chicago stood out in its resistance. When angry white mobs around the country attacked, injured and murdered groups of African Americans in the summer of 1919, Chicago’s black population fought back.

Black men in the city who had come home from fighting a war for their country — and who quickly realized they would be treated no differently than they had been before they went overseas — put up a defense against the violent mobs of white men rioting their communities.

Yet, as seminal of an event as the race riots were, most in the city have never heard much about them, let alone learned about them.

“While it happened 100 years ago, the factors that led to that still exist with us today,” Dowell said. “I think it’s really important that we understand our history and mark our history.

Speaking about the influence of the riots, Bey said the systemic segregation in their aftermath continues to shape the city today.

Bey cited as examples the building of the Dan Ryan Expressway as a tool to keep apart black communities on the east from white neighborhoods on the west; the history of redlining, which allowed white homeowners to prohibit the purchase, lease, or occupation of homes in their neighborhoods by African Americans; and more recently, school segregation and closings.

Mayor Lori Lightfoot, speaking Saturday at the annual Bughouse Square Debates at Washington Square Park on the Near North Side, echoed Bey’s connection of the riots to issues the city continues to struggle with.

“Yes, we have made progress,” Lightfoot told a crowd of a few dozen. “But not nearly enough. Our work to create a more equitable and just society has to continue.”