Charles Ellson wrote:
A start could be made by use of distinctive colours and
designs/symbols on a sufficiently large section of each note (like
Bank of England notes) but without departing greatly from the basic
green note. Changing sizes (if actually deemed necessary) could be
left until later with the process spread over a number of years.

The newest notes _do_ have distinctive coloring; for older notes a
cursory glance (by someone with normal vision) will distinguish between
them due to the different portraits, even the monochromatic ones. The
"large portrait" redesign in the 1990s solved most of the problems for
merely "vision impaired" folks, and color took care of the rest.

The issue at hand, though, is that neither of those things help the
blind figure out what they're holding; you need different sizes,
braille, or something similar that can be distinguished solely by touch,
and as of today US notes have nothing helpful in that area -- they all
feel exactly the same.

I recall some notes I had a while back when traveling (FRF? NLG? AUD?
NZD?) had clear sections that one could feel and, if given a few
seconds, determine the shape and thus what denomination the note was.
That's an interesting possibility as an alternative to different sizes
or braille. However, I don't know if that would be compatible with the
US's use of cloth notes...

S