eastern united states is a noun meaning "the region of the United States lying to the north of the Ohio River and to the east of the Mississippi River". It carries one recorded sense.
the region of the United States lying to the north of the Ohio River and to the east of the Mississippi River
Definitions, synonyms and semantic relations for eastern united states come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.