I'd imagine nuking Washington wouldn't change the US as a whole (perhaps you'd get another post-9/11 terror obsession, but I'd think the economic infrastructure

I'd imagine nuking Washington wouldn't change the US as a whole (perhaps you'd get another post-9/11 terror obsession, but I'd think the economic infrastructure would still remain rather intact). I think number of capitals isn't a very good measure of economic infrastructure: Monaco has some 30k people, but a non-capital city like Sao Paulo has 11 million. One could say "ok, let's drop Monaco and nuke Sao Paulo then", and then maybe nuke Boston and Sydney too while we're at it. But you're going to run out of bombs way before you run out of large cities.