Trade balance is just an income modifier. Imports v. Exports, essentially. I am not sure what exactly they based those numbers on though... I think we should play it as basically you are either exporting resources or manufactured goods, or you're importing them. Alternatively, you can exploit them from territorial/colonial possessions to give you positive balances as well.
As for infrastructure, I agree. I think I'll give a couple nations a bump for this stat.
So... how do we all have a positive trade balance?
I guess NPCs are running deficits?
Also, how are you handling movement of armies? Can I launch my 2.5 million man army straight across the Himalayas into India?
