The first woman to appear on U.S. currency was Marian Anderson, a renowned African American contralto singer. She was featured on the U.S. Postal Service's 1995 Marian Anderson stamp, which celebrated her contributions to music and civil rights. However, when it comes to actual paper currency, the first woman featured on U.S. paper money was Queen Isabella I of Castile.

Queen Isabella was depicted on the U.S. $20 bill in 1891, though her image was not widely circulated. This note was part of the Columbian Exposition series, which was issued to commemorate the 400th anniversary of Christopher Columbus's voyage to the Americas. The bill featured a vignette of Columbus, but Isabella's image appeared on the reverse side.

In terms of more widely recognized figures, Harriet Tubman is slated to become the first woman to appear on a regularly circulated U.S. banknote. The decision to place Tubman on the $20 bill was announced in 2016, aiming to honor her legacy as a leader in the abolitionist movement and her role in the Underground Railroad. The redesign has faced various delays, but there is significant public support for Tubman's inclusion.

Another notable mention is Lady Liberty, who has appeared in various forms on U.S. currency, symbolizing freedom and democracy. While she is not a specific historical figure, her representation has become iconic in American currency.

In summary, while Marian Anderson was the first woman featured on U.S. postage, Queen Isabella I was the first to appear on U.S. currency, albeit briefly. Harriet Tubman's upcoming feature on the $20 bill will mark a significant moment in U.S. history, as she will be the first woman to be prominently featured on regularly circulating paper money.

For further reading, you can explore resources such as:

• USA Today on Harriet Tubman and the $20 Bill
• U.S. Bureau of Engraving and Printing FAQ
• History.com on Harriet Tubman