I'm travelling to the US from the UK in a couple of weeks time. I have the correct type of passport. I have the Visa Waiver from last year and I checked online and it is still valid. I've lost the print-out of my Visa and I don't have a record of the Visa number, so I can't print out another copy.
My question is, do I have to have a printed version take with me or can US immigration access my Visa on their system.
Thanks.