We are travelling to Canada and the US in mid-2015 and wish to arrange local SIM cards for data. We will be away for about six weeks and initially will be moving back and forth between Southwest Canada and the US and then on to several major US cities.

Once in the past I went to AT&T in California and got a SIM in my iPad that gave me 5 GB over a month and it worked out well. We would like to do pretty much the same again but I have no idea how this will work given movement between Canada and US (we will initially be in Vancouver for a few days, then Seattle area for a few days, back into Canada for a few days, then back into the US for the rest of the trip).

Hopefully we won't need to organise SIMs separately for Canada and the US but have no idea how this all works or whether we can get plans that cover both areas etc.

Would be grateful for any advice on how to best approach this.