What's the purpose of a WikiProject tag on the talk page?
A tag lets editors know which projects they can ask for help,[1] and should have a clearly defined scope that relates to the topic, not to the editors that are currently editing the articles.[2] An article may fall under multiple projects.[3]
Why should WikiProject U.S. Roads (USRD) include all roads that have been built for, marked for, or used by through traffic?
Because these are the articles that road editors can help with, even if only in part.
