U.S. Treasury Secretary Janet Yellen and U.S. Treasurer Lynn Malerba attended an event on December 8 to see their signatures on a U.S. dollar, the first time the bill will bear the signatures of two women. For more than a century, it's been the tradition to have both the U.S. treasurer and the U.S. treasury secretary sign U.S. banknotes to make the bills legal tender. The notes are set for delivery to the Federal Reserve this month and will be in circulation starting in 2023.