In the Compromise of 1790, the United States capital was fixed at the location we still know today, Washington, DC.
What if the capital had remained in New York City or had been moved later in time to a more central location?
Episode 118: New Capital, New York
Another factor to consider if NYC is the US Capital is the fact there was considerable Confederate sympathy in the city (of course the same true of DC in many ways). But how might that have played into things Also, how about Staten Island as the new capital (AFAIK not developed much in 1789