Originally Posted by kms883

You clear US immigration and customs in Toronto so you'll probably want to be there before 5am. Usually there is not a huge line that early, but depending on the day (Mondays get bad due to business travelers) you'll want to plan to reach at least 90 minutes before your flight.

Good news is that you won't have to clear security again in Chicago.

No food on that flight unless you're in business (and even that is unlikely). Your reservation will tell you it's snacks for purchase or beverage service. Recommend hitting Tim Hortons if you're hungry.

Originally Posted by mapletree

+1 on getting there early. 6.15am should see minimal rush but you don't want to risk it. When the line is long it is VERY long. I'd get there by 4.45am at the latest. You'll probably get there and breeze through. But this way you're safe. Grab a Timmy's (Tim Hortons) once through security and relax...better than being stressed by waiting in the immigration line and maybe missing your flight.