Dans le New Jersey but à New York?

Question

Hi,In this lesson, we use Elle est à New York to say She is in New YorkBut in another lesson, we use J'habite dans le New Jersey to say I live in New JerseyNow I am a bit confused about the use of dans le and à with cities. Help!

Accepted Answer

Thy, I don’t think it is the prepositions causing confusion here but differentiating New York City and New York State.
This is a situation in which the particular French use of prepositions adds specific information  - ‘ dans le New Jersey ‘ confirms the reference is to the state of New Jersey (which does have a city named just ‘Jersey’).
On the other hand, we have both New York State and New York City -  ‘ à (la ville de) New York ‘ indicates that it is New York City referred to, not New York State. The latter would correctly be referred to with ‘ dans l’État de New York ‘. 
https://www.lawlessfrench.com/vocabulary/usa-states/