I use this example due to how short I-40 is not. If I look in OpenStreetMap, I am likely to see I 40, I 40B, I-40, and I-40B. Should interstate, US, and state highways contain the “-” or a space? Should the answer be a space, why?
Hi and welcome to OSM and the forum
The US-Community is more active on https://lists.openstreetmap.org/listinfo/talk-us . You might want to post your question there.
The space is the current separator. There’s no real strong reason other than inertia, but that’s a pretty good reason.
If they are consistent it’s easier to change them when making a map and so on. Any project to change them should start with getting lots of buy-in so that lots of people work on it and it happens in some reasonable amount of time.