We carry Nexus passes and use them for all crossings between US and Canada. A close reading of the rules shows that the inspector can require us to present a passport even though we have the Nexus Card. That has never happened, yet, but the passports are always available in whatever vehicle we are in.
They do freak out a bit when we cross with Nexus on the Niagara bridges with Texas plates and a NY address on file. It adds an extra question, "Why?"
Have lived near the border all my life and crossing is a regular experience, half my DW's family is from Canada.
