Niobrara River vs U.S.A.

Niobrara River and U.S.A. both are nouns.

Word	Noun	Adjective	Verb	Adverb
Niobrara River	Yes	No	No	No
U.S.A.	Yes	No	No	No

Niobrara River (noun)	U.S.A. (noun)
a tributary of the Missouri River	North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776