Kamala Harris surprises children at African American history museum for Juneteenth

Vice President Kamala Harris and second gentleman Douglas Emhoff made a surprise visit to schoolchildren at the National Museum of African American History and Culture to talk about the meaning of Juneteenth as the nation observed the new federal holiday on Monday.

Children and their families greeted Harris, the first Black woman to serve as the nation's second-highest executive, with cheers as she entered the room.

"Happy Juneteenth, young leaders," a smiling Harris told the children.

Juneteenth commemorates June 19, 1865, when enslaved African Americans in Galveston, Texas, were the last to learn President Abraham Lincoln had signed the Emancipation Proclamation two years earlier, freeing them from slavery. The date achieved federal holiday status last June, when President Joe Biden signed into law the Juneteenth National Independence Day Act.

"Today is a day to celebrate the principle of freedom," Harris told the children ages 4 to 10, "and think about it in terms of the context of history, knowing that Black people in America were not free for 400 years of slavery, but then at the end of slavery -- right? ... when the Emancipation Proclamation happened, that America had to really think about defining freedom ..."

"I would argue, it is our God-given right to have freedom," she added. "It is your birthright to have freedom, and then during slavery freedom was taken. And so we're not going to celebrate being given back what God gave us anyway" as the group voiced agreement, one person saying, "Amen."

She continued, "let this be a day that is a day to celebrate the principle of freedom, but to speak about it honestly and accurately, both in the context of history, and current application. That's what I'm thinking about today."

The National Museum of African American History and Culture opened in 2016, when it became "the 19th museum of the Smithsonian Institution," according to the museum's website.

After their remarks, the second couple talked with children as they worked on coloring books.

The surprise appearance on Monday follows Harris and Emhoff hosting the first-ever Juneteenth celebration at the vice president's residence, she tweeted on Sunday.

"I can think of no better way to celebrate Juneteenth than by spending time with the community," Harris said, sharing a photo of R&B duo sisters Chloe and Halle Bailey, who spoke at the event.

Biden released a statement on Sunday afternoon calling Juneteenth "a day of profound weight and power that reminds us of our extraordinary capacity to heal, hope, and emerge from our most painful moments into a better version of ourselves."

He added, "This is a day to celebrate, to educate, and to act."

Twenty-four states and the District of Columbia have passed legislation to recognize Juneteenth as a paid state holiday.

ABC News' Molly Nagle contributed to this report.