Helen Jones Woods grew up in rural Mississippi during some of the worst days of segregation. She spent her childhood on the campus of the Piney Woods School, which was founded in 1909 by her adoptive father, Laurence Clifton Jones, to provide a home and an education for orphans and other underprivileged children, most of whom were African American.

The school, which remains in its original location about 20 miles from the state capital, Jackson, became known for its musical groups, including the Cotton Blossom Singers and later the Five Blind Boys of Mississippi. After hearing an all-female swing band on the radio in the 1930s, Jones was inspired to launch a group at Piney Woods.

“My father heard the band over the radio one time,” Ms. Woods told NPR in 2011, “and said, ‘I’ve got a lot of girls here. Maybe I could start myself an all-girl band.’ ”

The group was formed in 1937, with the 13-year-old Ms. Woods, then known as Helen Jones, in the trombone section. At first, the teenage jazz musicians performed in Mississippi and neighboring states to raise money for the school. By 1939, they were appearing all over the country, including at the New York World’s Fair.

Within a few years, the band outgrew Piney Woods. In an act of rebellion, the musicians signed with a new manager, moved their base of operations to Washington and became known as the International Sweethearts of Rhythm. (For years, a building on U Street NW had a painted sign in the window: “Home of the International Sweethearts of Rhythm.”) The band members shared a house in Arlington, Va.

“My father was very much upset, but he didn’t say anything about me coming back,” Ms. Woods told the writer Leo Adam Biga for a blog post in 2010. “He sent his sister Nellie to bring us to Piney Woods, and she just said, ‘It would be wise if you came home, Helen.’ And I said, ‘No, I want to stay with the band.’ ”

Ms. Woods was 96 when she died July 25 at an assisted-living facility in Sarasota, Fla. The cause was complications of covid-19, the disease caused by the novel coronavirus, said her daughter Cathy Hughes, founder and chairperson of Urban One, the country’s largest Black-owned media company.

The International Sweethearts of Rhythm reached their height during World War II and were recognized by Downbeat magazine and by musicians as the premier all-female big band of its time — and perhaps the first to be racially integrated. The term “international” derived from the band members’ varied ancestries: Hispanic, Asian, Black, White and Native American.

The Sweethearts traveled the country on their private bus, “Big Bertha,” and performed at schools, fairs, ballparks and, especially, at theaters in Black communities. They appeared at the Apollo in Harlem, the Royal in Philadelphia, the Regal in Chicago and the Howard Theatre in Washington, where they set an attendance record by drawing 35,000 people in one week in 1941.

They shared the stage with such renowned jazz stars as Ella Fitzgerald, Billie Holiday and Dizzy Gillespie. The Sweethearts went on a USO tour of Europe in 1945, entertaining troops in Paris and occupied Germany soon after the end of World War II.

The Sweethearts had dozens of jazz and swing tunes in their repertoire, including a showstopping version of “St. Louis Blues,” by W.C. Handy, who once visited them backstage. They made several recordings and appeared in early music videos called “soundies” that captured their dynamic stage presence and musical energy.

Along with Ms. Woods as one of three trombonists, the band included several star musicians, including singer and leader Anna Mae Winburn, tenor saxophonist Vi Burnside, baritone saxophonist Willie Mae Wong, trumpeter Ernestine “Tiny” Davis and guitarist and bassist Carline Ray.

When alto saxophonist Roz Cron and other White musicians joined the Sweethearts during World War II, Cron later recalled, she sometimes wore dark makeup because Jim Crow laws in the South prohibited performances by mixed-race groups. Pianist and bandleader Earl “Fatha” Hines later called the group “the first Freedom Riders.”

The band often had to overcome sexist attitudes from audiences and male musicians, who questioned whether women had the strength and “chops” to play such physically demanding instruments as the drums, trumpet and trombone. Yet they earned respect on the bandstand, one tune at a time.

“That was a great band, a fantastic band,” jazz trumpeter Clark Terry told critic Nat Hentoff for his book “At the Jazz Band Ball.”

Even though the Sweethearts were widely known to Black audiences, they were all but unknown to White America.

“I knew of the band’s blazing tenor saxophonist, Vi Burnside, only because black jazzmen would tell me that she could stand on her own against Coleman Hawkins and other towering male saxophonists,” Hentoff wrote.

The end of the road came for the Sweethearts in 1949, with Ms. Woods still in the band, as she had been from its inception. In 1958, nearly a decade later, Hentoff first heard a recording by the Sweethearts.

“When I used to hear tales of the music created by these traveling ladies,” he wrote at the time in the Wall Street Journal, “I figured they couldn’t have been that good. But . . . they were better than their legend. So how come they’re not even mentioned in ‘definitive’ histories of big-band jazz? Maybe because no one believed that women could do such things.”

Helen Elizabeth Jones was born in Meridian, Miss., and believed her birthday to be Nov. 14, 1923. She later discovered a birth certificate, her daughter said, indicating that she was born Oct. 9, 1923.

Soon after her birth, she was sent to a White orphanage. When it became apparent that she was the child of an interracial couple, she was moved to a Black orphanage and adopted by Jones and his wife.

After the Sweethearts broke up, Ms. Woods settled in Omaha, where she briefly tried to continue her musical career in a jazz band and with a symphony orchestra. She was fired from the orchestra, her daughter said, when her dark-skinned father greeted her after her first concert.

Ms. Woods received a nursing degree from Omaha’s Creighton University and a master’s degree in social work from the University of Nebraska at Omaha. She worked for 30 years as a nurse and social worker in Omaha while raising four children.

Her husband, William Alfred Woods, died in about 1975. Survivors include four children, Robert Woods of Los Angeles, Jackie Woods of Sarasota, Cathy Hughes of Silver Spring, Md., and William A. Woods Jr. of Omaha; seven grandchildren; and a great-grandson.

The International Sweethearts of Rhythm had a reunion concert in 1980, but Ms. Woods, who had long since given up the trombone, did not perform. Gradually, their legacy was rediscovered by jazz historians and scholars of women’s studies. Ms. Woods appeared in a 1986 documentary about the group and in a symposium at the Smithsonian National Museum of American History in 2011.

The music and the rigors of the road made the band members “bond like a bunch of sisters,” Ms. Woods told Biga for his blog.

Music, she said, “was the way we made our living. It kept us from having to be a cook or a dish washer. It showed us an exciting time beyond the same old dull life. . . . Plus, we got a chance to see the world. That was our reward. It wasn’t money, because we certainly didn’t see any.”