To my knowledge, Emily Dickinson never visited New York CIty or Baltimore, but she did visit Philadelphia. I found information about an article about the visit, and the author’s abstract states this:
“In late winter 1855, Emily Dickinson and her sister, Lavinia, spent two or more weeks in Philadelphia visiting their second cousin, Eliza Coleman, and her parents. No letter from her describing their activities there has survived. This paper attempts to fill that void by examining Philadelphia's physical, social, intellectual, and cultural character at the time of their visit. Also considered are questions relating to Dickinson's friendship with Eliza Coleman and the origins of her longtime correspondence with the Reverend Charles Wadsworth of Philadelphia's Arch Street Presbyterian Church. The aim is to suggest how the trip may have influenced the poet's subsequent life and work.”
I tried to access the article but couldn’t – and I am a member of the Emily Dickinson International Society – so I’ve contacted the powers-that-be at the Johns Hopkins University Press to see if, indeed, I can download a copy.
In the meantime, I was able to see one page of the article which I have posted below. Once I have more info, I’ll post an update!