NicJim has pointed nearly all of the things to look for. The US model will have the serial number pressed into the back of the headstock. The imports have the serial number either screen printed on the back, or a silver sticker. But to boil it down...
US Cirrus *neck through* will have:
• ABM bridge
• pressed-in serial number
US Cirrus *bolt on* will have:
• Individual "finger style" bridges
• stacked-mid knob due to Mill preamp
If it's a bolt-on Cirrus, it's a US model. I don't believe they made an import Cirrus with a bolt-on neck.
Import Cirrus will have:
• neck-thru construction
• "BXP" on the headstock
• individual "finger style" bridges
• serial number will be screen printed or a sticker
Also, as NicJim said, the wood top is MUCH nicer on a US Cirrus. The BXP models have a cheesy, gloos veneer that looks nice at first glance, but is actually really cheap.