The music that uplifted and emboldened enslaved people in America as they struggled for emancipation inspired civil rights activists 100 years later as they fought for the Civil Rights Act to be made into law.

As New Orleans marks the 50th anniversary of the act’s signing July 2, 1964, the songs that inspired activists of both eras will be heard at the U.S. Mint, presented by National Park Service rangers leading the Underground Railroad Freedom Singers.

Started by rangers Matt Hampsey and well-known local musician Bruce “Sunpie” Barnes, the Freedom Singers perform traditional spirituals that enslaved people sang in America in the early to mid-1800s, many of which were revived 100 years later and adopted by civil rights activists. The program is free.

“Bruce and I developed a unit around the songs, and we use it at the National Jazz Park presentations once or twice a month,” Hampsey said. “As rangers, we get a good bit of latitude about programs we want to develop and offer, and because jazz is rooted in so many African-American music forms, the spirituals and freedom songs fit into the mission.”

No one today knows exactly what the songs sounded like, but Hampsey said that decades-old oral histories given by former slaves help authenticate the lyrics and melodies. Many of the spirituals live on today in black churches.

“One of the most interesting things we found out as we delved into the songs was that the lyrics often had double meanings and encoded messages,” Hampsey said. “Slaves had to be tremendously careful in their communications about gatherings, which were forbidden, and so would rely on lyrics that might suggest one thing to the slave owner and something altogether different to other slaves. The songs weren’t only outpourings of feeling or prayers, but also means of conveying information.”

Many of the songs that disguised resistance to the slave system were resurrected during the civil rights movement, Hampsey said. “Sometimes the lyrics were updated to suit somewhat different circumstances, but the message of resistance and protest would stay the same,” he said. “Sometimes the original verses remained the same in the 1960s, but new ones were added.”

Although most of the six songs the Freedom Singers plan to perform Saturday will be arranged by Hampsey and accompanied by instruments, one will be performed a cappella, with only clapping and stomping as accompaniment.

“That one will be the most authentic experience of what a slave spiritual probably sounded like,” Hampsey said.

To showcase the role of 19th-century slave spirituals in the 20th century fight for civil rights, the New Orleans Jazz National Historic Park recently released a two-disc CD set titled “Freedom is Coming,” with a booklet and liner notes about the 34 songs recorded.

Among other songs, the Underground Railroad Freedom Singers will perform “Many Thousan’ Gone,” a mournful piece that conveys the pain of the loss of loved ones; “Oh, Freedom,” a song that received renewed interest during the civil rights movement; and “My Mind Stayed on Freedom,” about the single-minded determination of slaves seeking emancipation.

Performers on the CD (some of whom will perform at the Mint) include Barnes and Hampsey, plus Al Bemis, Alex Bosworth, Tyrone Chambers, Stephen Dale, Leroy Etienne, Erica Falls, Elaine Foster, Michael Harris, Joseph King, Phillip Manuel, Joshua Walker and the Cornerstone Harmonizers.

Additionally, New Orleans’ own Ashley Renée Watkins and her group will be singing four spirituals.The jazz music portion will be rounded out by pianist Josh Paxton, who will also perform about four songs.

The performance by the Freedom Singers follows a panel discussion on the topic featuring Jackie Harris, director of the Louis “Satchmo” Armstrong Summer Jazz Camp.; Rev. Lois DeJean (sometimes called the “Queen of New Orleans Gospel”); and Dr. Dorothy Smith, a Dillard University historian.