Here is a sign that popped up in Half Day, IL on Milwaukee Ave. at Half Day Road last fall after a reconstruction project. Last week however they covered up the non-standard US-45 marker with a regular US Route Marker, bolting on the marker over the white on black 45.
Notice that the signs themselves are two single sheets adhered or silk-screened to the main panel, not individual banners and markers.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.n9jig.com%2Fimages%2Fus45.JPG&hash=01e019c37e4c22906e9aab698fecb414d8ed7e0d)
While I admit to liking the white numbers on the black US shield, this is rare indeed. IDOT (especially District 1) does not typically use one-piece assemblies. I'm guessing a contractor made this entire assembly.
Lately, when IDOT has been "redoing" major intersections, they have started using single sign assemblies. The replacement of the sign(s) at Archer and 55th split in the city is now a single sign, although this may be the city's doing.
I have seen similar adhered-sheet signs in other areas of Illinois, notably in the LaSalle/Ottawa area, but this was the first I have seen in the Chicagoland area.
I was more intrigued however by the white on black US Route marker. I like it, but it isn't compliant so I guess it had to go...
The new intersection at IL-25, Dunham Road, and Stearns Road in Kane County makes use of single-sheet signs as well. Not a fan, but not my call.