Are they just counting manufacturing and ag in that number? Wall Street moves a lot of money, and accounts for a lot of NY wealth. Illinois has a lot of auto plants and auto parts plants throughout the state, and companies like Deere and Navistar that export a ton of gear to the rest of the world, along with soy, pigs, and corn.

If they're counting by corp headquarters, don't forget McDonald's and Boeing are in HQ'd in the Prairie State, though I'd think IBM and the banks would offset that. It's an interesting number.

GDP is pretty specific, but I have no idea how Wall Street is counted.

GDP for countries is pretty specific, but who calculates "GDP" for sub-national units like states?

What I meant by the Boeing headquarters example was that it would certainly deceptively boost Illinois's GDP if they included all the receipts for sale of planes manufactured in Seattle or elsewhere in Illinois as a corporate number.

I've seen GDP stats for states and even cities many times. probably state governments (as taxing bodies) have a pretty good idea of what's going on in their states; maybe they're the ones calculating it? But I couldn't say for sure.

I don't buy it either. See this article, which takes Bureau of Economic Analysis figures and doesn't put Illinois in the top five for per-capita GDP, much less ahead of NY State. And as of 2005, only California and Texas had higher total GDPs than NY State.