US is not a word, it's an abbreviation. United States is the proper noun.
The noun 'Ohio' is a proper noun, the name of a state in the US; the name of a specific place. A proper noun is always capitalized.A common noun is a general word for a person, place, or thing. A common noun for the proper noun 'Ohio' is state.
"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
As it is the name for a specific thing, it is a proper noun.
The noun 'route' is a common noun, for example, This is the route to Boston. Any common noun becomes a proper noun when it is used for a specific person, place, thing, or a title such as US Route 66 or the TV show 'Route 66'.
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
Pencil proper or common noun
it's a common noun. a proper noun would be Spider-Man.
Proper noun or common noun
The noun cassette is a common noun.
a common noun?