Key:ele - OpenStreetMap Wiki is pretty vague when explaining what elements to add ele to, only saying to not tag objects where the elevation “is not an information of general interest”.
ok, but a single elevation value on a way or area only makes sense if the area or way is flat (roughly on the same elevation), this is implicit, and is a requirement from verifiability.
In parts of the U.S., it’s customary to associate a single elevation with a whole city regardless of topological variation within it. These elevations are posted at the city limits and at train stations.
Ideally, this elevation would be tagged on wherever the elevation was measured, but this location isn’t always obvious to us. Tagging this elevation on the place=city point may be misleading, as it implies a spot elevation at that point. Tagging it on the boundary relation that embraces the spot elevation would be less misleading, if a bit weird.
Anyways, the ele=* tag on the National Wildlife Refuge didn’t come from a city limit sign, or any sign for that matter. It’s a spot elevation from GNIS, based on an elevation model at a specific location where old USGS topographic maps labeled the refuge. We imported the refuge from GNIS as a point at that location, but later the point was conflated with the boundary relation. Since the spot elevation comes from an arbitrary spot on an elevation model, and the refuge has a diffuse geometry, the ele=* tag should’ve been deleted at that time instead of being copied over.