Sorry, but you don't always just "blow right through" with a green card. My husband has a green card and 1 out of every 4 trips I get the third degree and I'm asked multiple times how I know the man sitting next to me, where does he work, etc.We've gone down with a friend that's got a visa (she's from australia and not a citizen but been in the US for many years). We just brought a youngster down that had a passport card/id. At the border, it's pretty loose. If you have your US PassportCard or "green card", you blow right through. We've gone through before where they took 5 passports from me, looked at the 6 people in the truck and handed them back and waved us on. No worries - just don't expect to come back in without your docs.