I ran across this not that long ago. I hadn't seen one before. Didn't even know it ever existed, actually. Anyway, when I learn something, I have this sick need to share.

"Martha Washington is the only woman whose portrait has appeared on a U.S. currency note. It appeared on the face of the $1 Silver Certificate of 1886 and 1891, and the back of the $1 Silver Certificate of 1896. There have not been any women featured on U.S. paper currency in the entire 20th century."