It's been a while since I've ridden a train - but they x-ray luggage on trains now?
The last train I took near Portland and the like was the coast Amtrak from Union Station in LA all the way up to Seattle - then a bus through the border. This was all the way back 30 years ago for Expo '86 in Vancouver. I remember giving the border agents my *report card* as evidence of US citizenship and nobody had any problem with it. I was around 10 years old at the time.
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.