Years ago I worked at document management company.  There is cool software that can automate aspects of hand-written forms.  We had an airport as a customer - they scanned plenty and (as I said before) this was several years ago...On your airport customs forms, the boxes that you 'need' to write on - are basically invisible to the scanner - but are used because then us humans will tend to write neater and clearer which make sit easier to recognize with a computer.  Any characters with less than X% accuracy based on a recognition engine are flagged and shown as an image zoomed into the particular character so a human operator can then say that is an A.   This way, you can rapidly go through most forms and output it to say - an SQL database, complete with link to original image of the form you filled in.If you see black boxes at three corners of the document - it is likely set up for scanning (they help to identify and orient the page digitally).  If there is a unique barcode on the document somewhere I would theorize there is an even higher likelihood of it being scanned - the document is of enough value to be printed individually which costs more, which means it is likely going to be used on the capture side.   (I've noticed in the past in Bahamas and some other Caribbean islands they use these sorts of capture mechanisms, but they have far fewer people entering than the US does everyday)The real answer is: it depends.  Depending on each country and its policies and procedures.  Generally I would be surprised if they scanned and held onto the paper.   In the US, they proably file those for a set period of time then destroy them, perhaps mining them for some data about travellers. In the end,  I suspect the paper-to-data capture likelihood of customs forms ranges somewhere on a spectrum like this:Third world Customs Guy has paper to show he did his job, paper gets thrown out at end of shift. ------>  We keep all the papers! everything is scanned as you pass by customs and unique barcodes identify which flight/gate/area the form was handed out at, so we co-ordinate with cameras in the airport and have captured your image.  We also know exactly how much vodka you brought into the country. :)