WASHINGTON (AFP) - The one-time slave turned abolitionist Harriet Tubman was named on Wednesday (April 20) as the new face of the US$20 banknote, the first time an African American has featured on US currency.

A sweeping redesign of the US bills to be unveiled in four years will also protect Mr Alexander Hamilton's central place on the US$10 note, once thought threatened until Broadway's hit hip hop musical "Hamilton" made the 18th century US finance chief a modern-day star.

Mr Hamilton's latter-day successor, Treasury Secretary Jacob Lew, announced the changes slated for the Us$5, US$10, and US$20 notes after more than a year of lobbying and polling, with heavy pressure for a female figure to take place on a US banknote.

An open poll of more than 600,000 people had strongly favoured Ms Tubman, a hero to African Americans for her escape from slavery in Maryland in 1849 to help run the legendary Underground Railroad that helped thousands of slaves flee to freedom in the 19th century.

The announcement brought widespread cheers.

"A woman, a leader, and a freedom fighter. I can't think of a better choice for the US$20 bill than Harriet Tubman," tweeted Mrs Hillary Clinton, the Democrat seeking to become the country's first female president.

Mrs Clinton's rival for the Democratic nomination, Mr Bernie Sanders, echoed: "I cannot think of an American hero more deserving of this honour than Harriet Tubman."

The plan originally was to revamp the US$10 note in 2020, possibly having a woman share it with Mr Hamilton, while the US$20 bill, one of the world's most circulated banknotes, would wait another decade for redesign.

But the grassroots group Women On 20s launched a powerful campaign to get the US$20 note revamp sped up, with a woman featured, in time for 2020, the 100th anniversary of American women receiving the right to vote.

"The decision to put Harriet Tubman on the new US$20 was driven by thousands of responses we received from Americans young and old," Mr Lew said.

"I have been particularly struck by the many comments and reactions from children for whom Harriet Tubman is not just a historical figure, but a role model for leadership and participation in our democracy."

Mr Lew also came under pressure over the talk of changing the US$10. Mr Hamilton is a hero in the Treasury as the architect of the US financial system.

Mr Lin-Manuel Miranda, the creator and star of broadway musical "Hamilton", lobbied Mr Lew when the official attended the musical in New York. He later said Mr Lew had assured him that his fans would be happy with the decision.

Women and African Americans will feature more broadly in the remakes of all three bills. US currency traditionally has featured a president or one of the founding fathers like Mr Hamilton on the front and a monument on the back.

Women have only featured twice before: first president George Washington's wife, in 1886, and the native American folklore heroine Pocahontas in 1875.

The new US$10 note will depict a historic 1913 protest for women's suffrage at the Treasury and several women, black and white, involved in that campaign.

The backside of the new US$5 bill - which features president Abraham Lincoln on one side - will depict a number of historic events at his memorial in Washington, including Martin Luther King's 1963 "I have a Dream" speech for racial equality.

The choice of Ms Tubman pushed Mr Andrew Jackson, a southern slave owner and general who was US president from 1829 to 1837, to the backside of the US$20 note.

Mr Lew said the target for the redesigns, which are complicated by the need to employ the most modern anti-counterfeiting technology, was 2020.