Assume the position

I was driving back from Tombstone, Arizona to Tucson - see below for why - when I was directed into a checkpoint by border police. An officer signalled for me to stop the car. "ID please," she said. "Who are you and where are you going?"I told her my name and that I was heading for Tucson."ID please," she said. "How long have you been in America?". "A week," I replied, realising that my passport was in my bag in the boot of the car. "My passport's in the trunk. I'll just get it."
I moved to open the door of the car. Mistake. Her tone changed, with a note of urgency creeping in. "Stay in the car, sir." she ordered, fingering the holster of her gun. I saw other figures in olive green moving at the edge of my vision. I repeated my name, told her where I'd been in America, where I was going and what I was doing, and that my passport was in the trunk because British people don't carry ID. I was suddenly aware of how seriously they were taking this. There were five of them around my car, all with guns.
"Sir, stay in the car," she said. "This is a checkpoint. We need to see ID so we know who you are. Next time you go through one of these have your papers ready." She waved me through.

I'd been warned that the US borderlands with Mexico had changed and were now tense, hostile places. This officer was taking it all very seriously and I hadn't expected that at all on a day trip to a Wild West town. Getting shot by a jumpy border guard 40 miles inside the bloody border isn't in my life plan at all.