GEOFF BENNETT: One hundred and fifty-eight years ago today, Union Army General Gordon Granger arrived in Galveston, Texas, to inform the country's last enslaved people that they had been freed under the Emancipation Proclamation.

The day we now know as Juneteenth was formally recognized as a national holiday two years ago, due in large part to the activism of a 96-year-old retired Texas schoolteacher.

Opal Lee first gained national attention in 2016, when the then-89-year-old walked more than 1,400 miles from Fort Worth, Texas, to Washington, D.C., in a campaign to convince lawmakers to recognize Juneteenth as a federal holiday.

OPAL LEE, Activist: I just wanted it to be a holiday.

And I didn't know what else needed to be done.

I don't know if I would have tried to stand on my head to make somebody aware.

GEOFF BENNETT: Juneteenth commemorates the end of slavery in the U.S.

Even though President Abraham Lincoln signed the Emancipation Proclamation in 1863, Texas enslavers deliberately withheld the news.

On June 19, 1865, Union General Gordon Granger led some 2,000 Union troops, many of whom were Black, into Galveston Bay, where they announced that the more than 250,000 enslaved Black people in the state were free by executive decree.

The day came to be known as Juneteenth, a combination of June and 19th.

Now 96 years old, Lee says the message of Juneteenth is a simple one.

OPAL LEE: It's not a Texas thing and it's not a Black thing.

It's freedom for all of us.

And we are not free yet.

We have got too many disparities, I mean, the joblessness, the homelessness, the health care that some of us can get and that others can't, and climate change that we are responsible for.

We're not free yet.

GEOFF BENNETT: As part of her walking campaign, Lee trekked two-and-a-half miles each day, representing the two-and-a-half years Black Texans remained enslaved after the signing of the Emancipation Proclamation.

It didn't take long for word to spread and countless others to join her march.

And the campaign picked up momentum in the wake of demonstrations for racial equality after the killing of George Floyd.

JOE BIDEN, President of the United States: We are blessed.

We are blessed to mark the day in the presence of Ms. Opal Lee.

As my mother would say, God love her.

(APPLAUSE) GEOFF BENNETT: In June of 2021, President Joe Biden signed a bill to recognize Juneteenth as a federal holiday and acknowledged Opal Lee's singular mission.

JOE BIDEN: She's walked for miles and miles, literally and figuratively, to bring attention to Juneteenth, to make this day possible.

I ask once again we all stand and give her a warm welcome to the White House.

(APPLAUSE) OPAL LEE: To be in the White House with the president and the legislators and all of those good people, I could have done a holy dance, but my kids say, when I try, I'm twerking.

So I didn't.

GEOFF BENNETT: Asked about the best part of realizing her dream for Juneteenth, the retired schoolteacher is quick with an answer.

OPAL LEE: To see how eager the children are to learn.

And I think it's a travesty taking books out of the school.

We should be able to teach the good, the bad, the ugly, so it doesn't happen again.

GEOFF BENNETT: Opal Lee says we should honor our country's second independence day by reflecting on our shared history and future.

OPAL LEE: If people can be taught to hate, they can be taught to love.

It's not going to happen in a day.

You are going to have to work at it.

But I do believe, when we are all on the same page, we are going to make this the greatest country in the world.

GEOFF BENNETT: Hmm.

It is worth emphasizing that Ms. Lee started her walking campaign in her late 80s.

And, in the interview, she said that she wasn't sure that she would live to see the day where her dream was finally fully realized.

And that's one of the reasons why she's so grateful.

AMNA NAWAZ: Such a great interview.

Talk about an American hero.

GEOFF BENNETT: Absolutely.