Unfortunately, the route markers had the route number in smaller type than the abbreviation "FLA." inside a blue diamond. Of course, that meant the number was not very legible to a motorist passing at 50 miles an hour.
But it's a nice marker and if you shrink the abbreviation and enlarge the number, you can have a uniquely recognisable icon for the state of Florida. Here below are examples for the state and county roads.
Inspired by R. V. Droz's idea, I present some ideas for Michigan. I am using the existing Michigan Trunk Line (state highway) diamond and a silhouette of the state itself as a watermarque. Both University of Michigan (yellow and blue) and Michigan State (green and white) colors are used so that there is no favoritism.
One idea for Michigan Trunk Lines.
Another idea for Michigan Trunk Lines.
A third idea for Michigan Trunk Lines. I think this one is best.
Now the Michigan Trunk Line freeways (like M-59 Freeway, M-53 Freeway, M-10 John C. Lodge Freeway, etc.).
One idea for the Michigan Trunk Line freeways.
Another idea for Michigan Trunk Line freeways (I like the previous idea better).
Finally, the County Roads.
Same Trunk Line diamond and state silhouette watermark, FHWA county roads standard colors except substitution of goldfinch yellow for visibility where it counts.
These are colorised permutations of the existing black-and-white New York state route marker.
Like the first series, the state routes would adopt the colors of the 1970s NYS license plates and the county route markers would adopt the US FHWA standard county road colors, with two variances: there would be a watermark in a slightly paler blue, and the route number would be in goldfinch yellow, not US FHWA standard Spanish Orange (warning sign Yellow).
Two-digit route marker, square.
Three-digit route marker, short rectangle (Ht. by 5/4ths Ht.).
Three-digit route marker, long rectangle (Ht. by 3/2nds Ht.)
This is another sign series idea sent to RV Droz's website. It has both state route and county route markers. State route markers are in the color of the NY license plates of the 1970s. County route markers are same as for the FHWA standard pentagon county route marker, but the number is in goldfinch yellow for better nighttime visibility.
This is an idea for off-Interstates limited access expressways (freeways). It is patterned after the Quebec Autoroute design, and has the colors and two elements (shield and star) of the Massachusetts state flag.
This is the third series, based on the old Mass. Pike corporate logo, which in black text on white space was used as a reassurance route marker on the turnpike itself. Also on display in much smaller size at RV Droz's website. It's just a state route sign. No provisions to differentiate parkways, town roads, and special tourist routes. Same as the present plain rectangle, the sign for all the numbered state routes, regardless of roadway ownership and maintenance responsibility.
And this last would be for town-maintained routes, except when maintenance responsibility goes from state, to town, and back again. Only where the whole stretch, the first part, the last part, or a new extension is maintained by the town. Certainly not like State Road / County Road / State Road / County Road 865 in Fort Myers, Florida!
And now the same ones (well, the first three), but for mounting on the overhead directionals* and other big green signs:
Regular state routes.
* Overhead directionals: big green signs mounted on overhead sign bridges, or gantries.