US vs Mississippi River

US and Mississippi River both are nouns.

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

US (noun)	Mississippi River (noun)
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	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