MONTGOMERY, Ala. (AP) — Claudette Colvin, whose 1955 arrest for refusing to give up her seat on a segregated Montgomery bus helped spark the modern civil rights movement, has died. She was 86.

Her death was announced Tuesday by the Claudette Colvin Legacy Foundation. Ashley D. Roseboro of the organization confirmed she died of natural causes in Texas.

Colvin, at age 15, was arrested nine months before Rosa Parks gained international fame for also refusing to give up her seat on a segregated bus.

Colvin had boarded the bus on March 2, 1955, on her way home from high school. The first rows were reserved for white passengers. Colvin sat in the rear with other Black passengers. When the white section became full, the bus driver ordered Black passengers to relinquish their seats to white passengers. Colvin refused.

"My mindset was on freedom," Colvin said in 2021 of her refusal to give up her seat.

"So I was not going to move that day," she said. "I told them that history had me glued to the seat."

At the time of Colvin's arrest, frustration was mounting over how Black people were treated on the city bus system. Another Black teenager, Mary Louise Smith, was arrested and fined that October for refusing to give up her seat to a white passenger.

It was the arrest of Parks, who was a local NAACP activist, on Dec. 1, 1955, that became the final catalyst for the yearlong Montgomery Bus Boycott. The boycott propelled the Rev. Martin Luther King Jr. into the national limelight and is considered the start of the modern civil rights movement.

Colvin was one of the four plaintiffs in the landmark lawsuit that outlawed racial segregation on Montgomery's buses. Her death comes just over a month after Montgomery celebrated the 70th anniversary of the Bus Boycott.

Montgomery Mayor Steven Reed said Colvin's action "helped lay the legal and moral foundation for the movement that would change America."

Colvin was never as well-known as Parks, and Reed said her bravery "was too often overlooked."

"Claudette Colvin's life reminds us that movements are built not only by those whose names are most familiar, but by those whose courage comes early, quietly, and at great personal cost," Reed said. "Her legacy challenges us to tell the full truth of our history and to honor every voice that helped bend the arc toward justice."

Colvin in 2021 filed a petition to have her court record expunged. A judge granted the request.

"When I think about why I'm seeking to have my name cleared by the state, it is because I believe if that happened it would show the generation growing up now that progress is possible, and things do get better," Colvin said at the time. "It will inspire them to make the world better."