Black on White FM/RM Road shields

[national highway 1]

Hi, I have a question. I do like the Black squared outlined Texas FM/RM roads but I do like the black on white shields manufactured between 1956 and 1969. Anyone know why they were retired?

[NE2]

That FM 69 shield? Probably because of the bullet holes

[Brian556]

I read on old newspaper article that stated that this change, along with the US highway sign design change, were to improve readability/legibility of signs, particularly assemblies at intersections. In Texas, this change also involved moving the arrows to outside the route marker signs.

[Alps]

A lot of states used white-background shields during this time, especially for US highways. NY used them for everything, for example. States like Delaware were still using cutouts with a single black border rather than the black square. By the 70s, states were all using black squares without cutouts, with isolated exceptions (California, most notably).

[Scott5114]

The white outline US shield was part of the 1948 MUTCD. This was the first shield specified as 24×24in; cutouts were 16×16 inches. Accordingly the white-outline shield was designated as the "oversize" marker, and was supposed to be used at junctions only; the 16×16 cutout marker remained in the manual for use as reassurance shields. When the 1961 MUTCD came out, all markers were made to be 24×24 by default and the backgrounds flipped to black. That change was probably made for legibility reasons. The cutout shield was retired at this time–probably for legibility reasons as well, but it could have very well been just because having two different shield variants for two different purposes was confusing, and upping the cutouts to 24×24 was probably more expensive than it was worth.

As for state shields, a lot of states were probably just mirroring the changes made by the feds with the US marker so there wouldn't be two very-different looking shields on one assembly.

[US71]

A lot of states used white-background shields during this time, especially for US highways. NY used them for everything, for example. States like Delaware were still using cutouts with a single black border rather than the black square. By the 70s, states were all using black squares without cutouts, with isolated exceptions (California, most notably).

Arkansas used them, as well, for both US and State highways