I'm not buying into the Rothchilds conspiracy stuff, but in my studying of the start of the Civil War, it certainly appears to me that wealthy men of New York had the most to lose from an Independent South.
I think New York's excessive influence in Washington began with the election of Lincoln, and has continued ever since. I think the Media broadcasting systems are located in New York precisely so that influential people can keep an eye on them, and insure they put forth "news" that is in the best interests of those people who like Big Government in Washington D.C.
The Delano family also made millions during the Civil War when they saw to it that the US Army Medical Corp had supplies of Opium. They, among many others, were big war profiteers.
And that fits too, of course.
I agree. They needed a center of power for control purposes and NY fit the bill.