USA vs Mississippi River

USA and Mississippi River both are nouns.

Word	Noun	Adjective	Verb	Adverb
USA	Yes	No	No	No
Mississippi River	Yes	No	No	No

USA (noun)	Mississippi River (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	a major North American river and the chief river of the United States; rises in northern Minnesota and flows southward into the Gulf of Mexico
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