White ones are a guess at signs used from 1922 until 1924; yellow ones are based on photographs of signs used from 1924 through at least the 1930s, and perhaps later. Although yellow stop signs were used until 1954 when they were changed to the now-common white on red, the later ones used a different font.
Of course, many of these signs persisted past their end date; especially in out-of-the way locations.
Coming soon(tm) to a DLS near you....
Last edited by Pencil
on Wed Feb 09, 2011 9:09 am, edited 1 time in total.