Celebrities who are calling for Juneteenth to be a national holiday, including Taylor Swift and Lupita Nyong'o

The singer also tweeted that she would keep educating herself "on the history that brought us to this present moment."

"The liberation Juneteenth commemorates is cause for celebration, but it also reminds us how equality can be delayed," the musician, actor, and entrepreneur wrote in the Washington Post

"My heart is shattered by the ongoing injustices in this country, incited by its long history of racism that has led to deadly outcomes for too many of our people," he wrote. "This country must change."

He said the day could be observed by celebrating both Black Americans' first "first step toward freedom" and their contributions to society, ranging from Black Wall Street to music to excellence in sports.

The "Us" actress shared a photo of Opal Lee, calling the 93-year-old the "force behind the movement to make #Juneteenth a national holiday."

Nyong'o also encouraged followers to sign a Change.org petition to support Lee's fight.

Takei is best known for his role in "Star Trek" and his advocacy for the LGBTQ community and Japanese Americans.

The Oscar winner shared his message next to a picture noting that Juneteenth is "when America became a more perfect Union," meaning "all men are created equal."

Read more:

• How 15 celebrities are teaching their children about systemic racism and police brutality
• How Juneteenth, the day commemorating the end of slavery in the US, finally became recognized as a holiday by major companies like Nike and Lyft — and landed in the center of a Trump controversy