eastern vs eastern United States

eastern is not a noun while eastern United States is a noun.

Word	Noun	Adjective	Verb	Adverb
eastern	No	Yes	No	No
eastern United States	Yes	No	No	No

eastern (noun)	eastern United States (noun)
	the region of the United States lying to the north of the Ohio River and to the east of the Mississippi River

eastern (adjective)	eastern United States (adjective)
relating to or characteristic of regions of eastern parts of the world
of or characteristic of eastern regions of the United States
lying toward or situated in the east
from the east; used especially of winds
lying in or toward the east