Rocky Mountainsa is the singular genitive of Rocky Mountains.

Rocky MountainsN

Rare in texts

Norwegian Bokmål

Rocky MountainsNx

Nordsamisk-norsk ordbokdict-sme-nob/src/N_Propgeo_smenob.xml:37521Edit on GitHub Suggest

Case	Sg
Gen	Rocky Mountainsa / Rocky Mountains
Ill	Rocky Mountainsii
Loc	Rocky Mountainsis