WI: NYC US capital?

The US Consitution calls for a Federal District 10 on a side.
The get This -Either- NY state gives away NY City -or- the Consitution is amended.

The constitution says Congress has the power to purchase a ten square mile Federal District, not that it has to, and it has to be willingly ceded by the state. There's no way New York's going to just give away half of Manhattan.

Edit: This is the relevant bit of the Constitution:
The Congress shall have Power ... To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten Miles square) as may, by Cession of particular States, and the acceptance of Congress, become the Seat of the Government of the United States, and to exercise like Authority over all Places purchased by the Consent of the Legislature of the State in which the Same shall be, for the Erection of Forts, Magazines, Arsenals, dock-Yards, and other needful Buildings; And
 
If there is a Civil War in this timeline (which I suspect would be even more likely here than in OTL), I suspect it would be a lot tougher to keep the Southern states from leaving for good. Irreconcilable differences and what not.
 
You would still have skyscrapers. Part of the reason New York has so many is because southern Manhattan is made of solid rock, well suited for the bearing of structural loads.

But when DC was being planned, they modeled it on the city of Paris with its wide roads and low buildings. It is possible that Manhattan will start being planned in the same way and even though the area may be ideal for skyscrapers, they'll be ignored in exchange for the importance of having the capital seem worthy of the nation.
 
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