erm, cant really answer the question, but I did wonder the same thing. I suspect you need a tech/civic state before you can cash rush (like in Civ3, you need an appr. government) but I dont know if that's correct. Mostly because I never read manuals. 
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I fed my Dog the American Dream
Well, he rolled over and he started to scream
He said, I dig the taste of salt but it don't keep me alive yeah, yeah
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