The US Departures Area is in the west end of YOW (actually northwest). Enter the first door as you drive up.
Chronologically, this is the process:
1. Check-in (either on-line, kiosk or at a check-in desk). There should be blue US declaration forms scattered about (unless you use Global Entry).
2. Proceed straight ahead.
3. Queue for luggage screening (assume you will have a checked bag) and drop your bag.
4. Queue for security screening.
5. Queue for US CBP immigration processing. Once processed you have now been "admitted" into the US and will be treated as a domestic arriving PAX at EWR.
6. Take the escalator down into the US Departures gate area.

Gate area has a mini Tim Hortons, a restaurant, and a typical airport all and sundry shop.
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13F