How about Alcatraz Island?
How much networking is done between departments, though? (Dinners and other functions where people mix, mingle, and discuss work while “off the clock?”)
Native American protestors, lack of a road leading to it absent supervillain attacks, implausibility of maintaining a no-fly zone over San Francisco, blocking a major shipping lane, and not big enough.
I was going to suggest Treasure Island, but discounted it for all those except size (really, there’s barely enough bridge access for the city; taking up more for the nation’s capitol would require more bridges, and that ain’t gonna happen).
… a Better place, without fail.
In 360° , there isn’t a single move that can be made that isn’t Upward.
Yep, unfortunately it’ll be a pretty deep impact…like that movie with the comet, I forget the name.
The Bus That Couldn’t Slow Down
??The only part that was Virginia has been ceded back and is now “Roslynn, VA.” The rest of the District is embedded in Maryland.
The Government would start out inside Mt. Weather, VA. From there they’d be moved to Denver International Airport as soon as it was safe to do so. Those who were out of town would go straight to Denver.
I would assume that the city of Denver would eventually subsume the whole operation. By the time there was any decision to be made, all the contractors would already have obtained space and moved operations to the city. They’d lobby hard to stay put, and they usually win.
It’s hard to say whether a comet would prevent rebuilding. A Tunguska-style impact could easily knock down every single building without leaving any crater. Rebuilding might even make a lot of sense; I assume that an impact like that would even leave some things like utilities and pavement intact or repairable.
If there is a giant crater, then rebuilding might not be possible.
I don’t see DC moving very far, though. There are tons of lobbyists and other government support personnel who commute from cities all over the region. That puts a lot of momentum on something near the current location… and when everyone starts fighting over who’s state should get the capital, I think momentum will wind up being more important than negotiation.
Anyway, if I had to pick some place other than the current location, I think New York or a newly created suburb of it. The proximity to Wall Street and the United Nations makes sense, and New York is close enough to the current DC to somewhat satisfy the momentum consideration (especially if we pick a location perhaps an hour outside of NY in the direction of DC, meaning some lobbyists are only looking at 2-3 hrs to the new DC).
I didn’t read all of the replies thoroughly, but one thing I didn’t see mentioned was that DC was NOT in any state, and it was designed that way. The Federal Government was supposed to be placed in a “neutral” location to (I know, don’t laugh) keep it free from undue influence of the state in which it resided.
So in any place chosen, the state would have to cede that land into a new non-state based district. What state would want to cede a large chunk of land to the Federal Government? So it would also (?) have to be on the edge of the state to keep up the idea that the new district is not still part of the state that gave up the land.
J.
Combining the factors of
(1) near the center of the country, as many others have said,
and the nearly-opposing criteria of
(2) existing resources including transportation but
(3) lots of empty land, we get…
East St. Louis.
Located on the highways and railways leading into St. Louis, with the resources of St. Louis across the river so it’s not expensive construction in the middle of nowhere (cough North Dakota oil wells cough), but with lots of empty former-industrial land along the riverfront. Yes, its brownfield land at best and Superfund sites at worst, but who better to afford the land cleanup than the Federal government building its shiny new capital? 
And I doubt Illinois would oppose ceding East St. Louis for the requisite 10 square mile district. 
It’s going to be an economic benefit to any state to have the capital or a large federal district located there so states aren’t likely to object as long as it doesn’t involve taking already valuable land.
I really think you’re as wrong as you can possibly be with your observations. Of course we need a State Department HQ. But it doesn’t necessarily have to be located adjacent to the Dept. of the Interior HQ.
This doomsday scenario would be an excellent opportunity to physically decentralize the government.
Let’s go somewhere and talk about my plans for smaller schools, too.
Not to rain on the parade, but New Madrid Fault (more at New Madrid seismic zone - Wikipedia ) might be a factor in the decision…
Also a vote against one I previously mentioned (not 100% seriously, though): Memphis. 
I’d say stick them in a corner of Alaska to keep an eye on the Russkies, but I’m sure that that large an influx of hot air would be seriously detrimental to the environment.
Second choice would be to Detroit. They’re pretty much screwed passed the point of no return so the only real option for them is to completely rebuild/repurpose the city.
Charlotte NC.
The White House would be inside the cubical farm of Bank of America HQ.
What, 50+ posts in and nobody picked up on the freudian capital/capitol thing?
BTW, here in Holland the constitution says Amsterdam is the capital but the government is here in The Hague. How’s that fair?
More to the point, how likely does anyone really think it is that The Scienticians would waste this opportunity to advance the human race and warn Washington DC of the incoming? Sometimes we must sacrifice small virtues to attain great ones–scientists get that.
Another idea; move the capital to Detroit and convince the Canadians to move their capital to Windsor, so the capitals are adjacent.
I second Detroit. It may be the only thing that can save that city.
I’m jumping on the Denver, or at least Colorado, bandwagon.
A - there is plenty of open land in the area that could be ‘eminent domained’
B - there is already a secure military complex (Cheyenne Mountain)
C - perhaps they could take over Colorado Springs. It’s the seat of the Air Force academy and filled with citizens who are quite favorable to the government and would probably welcome it with open arms.
D - the altitude offers protection from a number of natural disasters. While we do have natural disasters here, they are few and far between - mostly wildfires and occasional flooding
E - it’s centrally located. While not necessarily in the exact center of the country, it’s a commerce and transportation hub for the center of the country west of Kansas City, with high-capacity airports, highway systems, and other infrastructure needs.
The only really big problem that might result is water shortage. But the government could always take back the water originating in Colorado that is currently being shipped elsewhere which would solve the problem. Of course that would leave several other states dangling, but when has that ever stopped the government from taking what it wants?