Civil rights pioneer Rosa Parks (file photo)

African-American leaders are mourning the death of Rosa Parks, a woman whose small act of defiance 50 years ago sparked the growth of the civil rights movement in the southern United States.

Rosa Parks, who died Monday at the age of 92 at her home in Detroit, has been an icon since she boarded a city bus in Montgomery, Alabama, on December 1st, 1955, and refused to give up her seat to a white person, as required by the law at the time. Her arrest and conviction for refusing to obey a bus driver prompted blacks in Montgomery to boycott city buses for more than a year.

The boycott, led by a young Martin Luther King Jr., was one of the first widespread public actions against discrimination. The Reverend Joseph Lowery, who suceeded King as president of the Southern Christian Leadership Conference, called Mrs. Parks the queen mother of the civil rights movement.

"She sparked a revolution that introduced the era of self-determination in the struggle for justice in this country," Mr. Lowery says.

Civil rights leaders who knew Mrs. Parks praised her for being courageous, especially considering the racial climate in Alabama in 1955.

Andrew Young, a former mayor of Atlanta and former U.S. Ambassador to the United Nations, remembers Mrs. Parks was quiet, dignified and humble.

"It was because of the type of person Rosa Parks was. Nobody could imagine her doing anything even discourteous to anyone. She was always as sweet and was mild-mannered, but very strong," Mr. Young says.

Today, leaders of the struggle for racial equality worry that Mrs. Parks' defiance will be forgotten among young people who do not remember the time when overt segregation and racial intimidation were widespread throughout the South.