The US Congress authorized to spend $72.4 billion for the Global War on Terror through FY2006 (not only for the ongoing military operations in IRAQ).

So (72.4 billion / 365 ) / 24 = 8 264 840.18 $/hour

Chris Jordan made three 8.5×3.5feet horizontal panels

containing $12.5 million in one-hundred dollar bills.

(12.5 million / 8 264 840.18) * 60 = 90.7458564 minutes

With those panels you can figure out the American cost of the “Global War on Terror” of every 90 minutes!

Here some more (clickable) details: