I had to send my passport out to get renewed and at the time didn't have any international travel scheduled for a few months. Now a client in Toronto wants me to visit them in late January and it's unlikely I'll have my passport back by then. I have NEXUS, but I've never tried to cross the border with just my nexus card and not my passport (I'm a US Citizen). Is this legal - both via land and air crossing? Has anybody actually tried to do it?