Yeah I prefer to use my Nexus card as well, but it pisses me off how some TSA agents won't accept it... If I had more time I would argue with them on the issue, but I'm the type of person who gets to the airport an hour before the flight lol, so I gotta rush.

Really? I figured the internal checkpoints were only in the American Southwest. Where in Florida was the checkpoint if you don't mind me asking?

It was at the Hollywood, Florida train station. The southbound Amtrak train had just pulled in. There was a white van pulled up next to the station and there were 4-5 agents milling about the crowd asking questions. They would randomly walk up to people and start asking questions. They asked me if I was a US citizen and they were paging through passports and checking ID's. I watched the whole thing go down, as I waited for the baggage cart to come around. One couple was eventually detained. There were also people waiting for the local commuter train who were caught up in it, as well.

The highway stop wasn't in the Southwest, it was in Vermont. The airport stop was in upstate NY. Although I wasn't stopped, there were agents standing by the TSA checkpoint pulling people aside.

Should they give you any hassle, which I can't imagine them doing over a shiny new passport, ask them for the passport, open it to the information page, point to the date of issue, and say "It's brand new you idiot, that's why it looks new"

I still ask the $64M question:

Unless you're driving, there's no must-carry photo ID law in the USA. But permanent residents "must" carry their green cards. How do you tell citizens and permanent residents apart?

I suppose they can't tell on the spot, but I am sure they have ways to figure it out by running your name through some kind of database if they really wanted to. If you said you were a citizen when you really weren't one and they caught you in a lie, it seems like you would have even bigger problems IMO.

My gf is a not a US citizen and while on a trip to Arizona I discovered that she had left her green card back home. We drove through a border patrol checkpoint that are scattered throughout AZ (Not at the border) and they asked both of us if we were US citizens. When they discovered she left her proof at home, she was quickly hauled off to jail. She was the only non-Mexican in the jail so she was somewhat better taken care of, it seems. It was a Friday evening and they told me they were taking her to Yuma and she would be there until she could see a judge on Monday. Fortunately, someone took the time to figure out she was in the US legally, so they let me pick her up after about 18 hours in the cell. After that experience I would say, carry your green card.