While doing research for my recent 1947 Interstate Highways map recreation, I stumbled across some scans (PDF link – 0.3MB) of American Association of State Highway Officials (AASHO) road sign specifications dated from the 1920s. The very first page has a dimensioned drawing of the then brand new U.S. Highways shield that I find extremely interesting, as it doesn’t quite match the the shield as it actually first appeared on real world signage in 1927. Some further research seemed to reveal that this drawing is of a design prototype (of a theoretical Route 56 in Maine) that AASHO discussed in meetings during 1926. The drawing itself is pretty rough, with dimensions that don’t match the actual size of the drawing and completely different shapes for each side of the now-familiar six-point shield, so I redrew it accurately according to the given dimensions in Illustrator.
I had to compromise a bit with the shape of the shield because the left and right sides were drawn so differently in the original drawing, but it seems to be a very similar shape to the final 1927 specifications; perhaps with just a little less scalloping with the top curve on each side. As seen in the comparison image above, the main differences between this prototype and the 1927 version are the thickness of the black borders, which are 3/4″ and go right to the edge of the cutout shield shape. By 1927, these had been reduced to just 3/8″ and were inset a further 3/8″ in from the edge of the cutout. I suspect that this was a production-based decision, as many early shields were embossed by a die before being painted, and embossing right to the edge of the shield may have been problematic.
The 1927 shield also uses a simpler, squared off “S” instead of the rounded version seen in the 1926 prototype, and the height of the “US” lettering was reduced to 2″ from 2-1/8″. The height of the route number remains constant at 5″, but the form of the slab type is a little different. Overall, the prototype looks a bit dark, heavy-handed and unbalanced compared to the “classic” 1927 version, but it’s certainly interesting to see one of the earliest steps in the shield’s evolution.
1948 saw the replacement of the simple “slab” typeface with the Standard Alphabet for Roadway Signage (also known as the FHWA Series or Highway Gothic), while the 1961 revision dropped both the state name and the cutout shield in favour of a larger route number and a square sign with a black background behind the shield shape. The last revision in 1970 changed the shape of the shield itself, allowing for more usable width (and wider numbers) within the shape.