Originally Posted by
sethb
I was going the other way (US to Canada, US citizen with NEXUS) and Delta told me that I couldn't fly without a passport. When I've flown to Canada, they've always required me to show my passport before boarding.
Delta's documented policy is "passport required", so they'd be a poor choice of operating carrier if one had to fly US/CA without a passport.
http://www.delta.com/content/www/en_US/traveling-with-us/planning-a-trip/international-travel/traveling-from-the-u-s.html
"
A passport is required for ALL international travel." (emphasis in original)