You dont need to stop the stock market to destroy the economy. There are over 10 million people who live in or near Chicago and every single one of them, including me is packing up and leaving after the two weeks are up. Say goodbuy to companys like Motorola, Boeing, and countless others who are based near Chicago, whos employess are dead or gone, and their offices and plants are radioactive. Not to mention that cash is only worth cash if you believe that the US government supports the dollar. The first thing i do if their is a nuke attack in a US that i dont like in is go to the bank and take out every cent i can. (im 19 and a college student so its only like 4K). Losing 4 of the biggests cities would ruin the economy. We'd survive but many would starve because of transportation problems.
The cleanup alone from one nuke in Chicago could bankrupt the nation. Get some food, some water, and head for a spot with a friend who owns a farm. The other option is for churches to network -- but they don't even do that in Hurricane disasters. I've often seen Churches in non-evacuation zones sitting empty while their elderly members sit in impersonal high school gyms. Something has to give in this "me first, me only" country. I hate to think the only time we'll come together is when we starve together after an attack.
True to a limited extent. Alot of people outside the immediate fallout areas will stay, others will return. The most likely scenerio seems to be a small nuke, with a relatively small area rendered level or uninhabitable for long. The companies you mention have other facilities and most large companies also now have at least limited redundency in their data systems. Will it cause a depression, probably, will it sink us? No way. We can survive multiple hits on major cities.