Alright, so I was doing a mini-TL, and part of it is that, while the Union is ultimately victorious, the Civil War lasts about a year longer and the Confederates manage to capture D.C. early on and hold it for a few months before the Union forces recapture it, however do to the Confederates purposefully damaging things and the city literally becoming a war zone much of the city is heavily damaged and by the end of the war the civil population has shown little interest in returning and even early on their are those who advocate creating a new capital in the North as a way to spite the South.
Anyways, in general where is the most likely place for a new capital city in the North in a scenario like this in your opinion?