Airline baggage allowances differ
 

Very interesting. Flight from US into Montreal on NWA allowed 2 free checked bags, consider Canada international. However, return on Continental makes travel to/from Canada follow under domestic baggage guidelines (i.e., fees!) May have been tempted to work harder for NWA return had I realized that earlier... was surprised that different airlines had different 'considerations' for the US-Canada travel!

Good observation - it's about competition. Canadian airlines do not charge for baggage checking and NWA sees itself in direct competition - and as a result I use NWA from Canada to the US and back. I also use Southwest within the US and avoid most those who do charge whenever possible. If the baggage charge is annoying, select the airlines that don't have one. Incidentally, I have wondered if the merger with Delta may cause a change at NWA or at Delta. Let's hope the wisdom of NWA prevails.

Airlines never seem to be able to figure out whether flying transborder between the US and Canada is "international" or "domestic," particularly when you add preclearance into the mix.

When I'm flying to Canada, some airlines want me to check in at international, others at domestic. It's kinda silly.