(Historic?)
(wrt banners).
Speaking purely of US Routes here (there might be state/provincial routes that have historic banners) but the routes aren't really bannered in the typical way, but rather the shields have the word historic in them. I may not be very familiar with banners, but I know enough to know that typically they come on their own separate panel (save for Business Interstates, which have their own shield, of course).
The shields for historic US routes (typically, but far from universally*) take this form, with a state name and the specific number of the route:
They do have some date-based banners in the form 19xx-19xx on Historic US66. And NM has "PRE-1937" banners on the route via Santa Fe. There's also a "SPUR"-bannered route. As such, the Historic bit being a banner for our purposes would be hard to deal with.
*see, for instance, MO's blue signs