Sorry, I should specified which kinds of designations I speak of, like NHS (National Highway System) designations. These for example are the highways that the FHWA has deemed the most important to the country logistically, usually those that links major industrial and/or transport hubs. Sometimes, however, a highway number designation can be relevant to the road's importance, like an Interstate or U.S. Route, and even state routes in some states or in rural areas of a state like Nevada, but not always. Highway numbers can and should be taken into consideration on a case-by-case basis but in urban areas like Las Vegas than can almost always be ignored since they're more relics of the past and now only reflect who maintains the road rather than how important it is or a sign to be used for navigation.

I would say that it may not be that necessary to make a list of state highways in Nevada, as Wikipedia's list can be used if needed—but if you were to go about creating a proposal for the community, you can create a page on the OSM Wiki.