Giving employees a day off may not seem like the top way for multibillion-dollar companies to fight systemic racism. But a new trend in corporate America—the declaration of June 19, or Juneteenth, as a company holiday—makes a powerful statement, according to historians.

Juneteenth celebrates the date in 1865, more than two years after the Emancipation Proclamation, when enslaved people in Galveston, Texas, learned that they had been freed through Maj. Gen. Gordon Granger’s “General Orders, Number 3.” The day is the oldest commemoration of the end of slavery in the United States, but it hasn’t been honored as a holiday or taught in history classes throughout much of the country.

Last week, Twitter and Square became the first major companies to announce they would make the day a paid holiday for their workforces. The duo were quickly followed by Fortune 500 companies like Mastercard and Target; media companies like the New York Times and Vox; and fellow Silicon Valley and tech firms like TikTok and Lyft. Some companies committed to an annual holiday, while others made the change for this year only. About 200 total companies have now pledged to honor the date with a paid holiday.

The gesture has resonance beyond its show of solidarity. The original Juneteenth proclamation was, at its core, about labor, says Tamika Nunley, an assistant professor of American history at Oberlin College who studies slavery, gender, and the Civil War. The first, most often quoted sentence of the message informs “the people of Texas” that “in accordance with a proclamation from the Executive of the United States, all slaves are free.” But the rest continues, “The connection heretofore existing between [former masters and slaves] becomes that between employer and hired labor. The freedmen are advised to remain quietly at their present homes and work for wages.” The message is meant to inform formerly enslaved people about the “new labor relationship,” Nunley says.

“There’s no other place that’s more fitting to acknowledge [Juneteenth],” says Nunley of modern-day employers.

The Juneteenth document also warns formerly enslaved people “that they will not be supported in idleness,” a message “controlling how they respond to Juneteenth,” Nunley adds. Companies, then, sending a clear signal that the day is one for celebration and not for work adds another dimension to the decision. “The order was designed to silence them—telling them to be quiet, not to be idle,” she says. “It makes the celebratory component of Juneteenth that much more important.”

Juneteenth’s closest equivalent among the holidays traditionally acknowledged by corporate America may be Labor Day, Nunley adds. The labor movement fought for the date honoring workers, which became a federal holiday in 1894. No other holiday on the American calendar specifically honors the end of slavery.

Of course, giving employees a day off for Juneteenth is only as meaningful as a company makes it through a broader commitment to racial justice. “Is it just a holiday, or is it a signifier in recognizing how systemic racism and inequity has constrained employees’ lives on all fronts?” Nunley asks.

The movement in corporate America to honor Juneteenth may contribute to more widespread recognition, including the longtime goal of a federal holiday. Almost all 50 states recognize Juneteenth as a holiday, but that doesn’t mean they provide a day off for state employees, as for other holidays. Some, including New York, have moved over the past several days to further honor the date as a paid holiday for state employees. Campaigns including HellaJuneteenth and the National Juneteenth Observance Foundation have long pushed for an acknowledgment from the federal government; their efforts have gained new momentum over the past few weeks.

The movement among corporate leaders to acknowledge the day’s significance to their workforces has been unprecedented. Says Nunley: “This is something entirely new for corporate America.”