Denominations of U.S. paper currency are currently indistinguishable except by sight. This causes difficulty for the sight-impaired, who often have to rely on others to verify amounts or sort bills.
Introducing a distinguishing tactile element to different bills, such as embossing or different sizes, is a simple step that can be taken during the next redesign of bills that would make a large difference in the lives of the more than six million sight-impaired people in the US.