Harriet Tubman will grace the new $20 bill as Andrew Jackson takes backseat

Lew also announced Wednesday that Andrew Jackson will move from the front of the $20 to the back, making way for Tubman. She'll become the first black woman ever to front a U.S. banknote.

Tubman, who died in 1913 at the age of 91, escaped slavery in the south and eventually led hundreds of escaped slaves to freedom as a "conductor" of the Underground Railroad. After the slaves were freed, Tubman was a staunch supporter of a woman's right to vote.

"What she did to free people on an individual basis and what she did afterward," Lew said. "That's a legacy of what an individual can do in a democracy."