Do you mind explaining what you are referring to? I'm a bit ignorant of this era of US history. I thought the east coast was the "original" US - that is, the thirteen colonies. Specifically New York was most definitely "made" by this point, even before the US was a thing. The New York stock exchange was founded in 1792, just 16 years after the country was founded. And trade was always big in New York. I don't know much about the rest of the east coast so I may be missing some larger historical context here but I was under the impression that NY was the most important sate by far on the east coast and continues to be so.