Guidance to Nationals in USA with green cards wishing to travel to Canada
Grenada – Lawful permanent residents of the U.S. with valid Green Card
You need an eTA to visit or transit through Canada by air if you are a lawful permanent resident of the U.S. and have a valid alien registration card (Green Card).
Note: you will need a passport from your country of nationality to apply for an eTA.
What you need to complete the eTA Form
Instruction for Completing online eTA Form