PDX-XXX (Vancouver, Seoul/Taipei/Bangkok, Japan),
and then of course there are the SLC-Canada routes that ASA may fly, but no longer mainline DL. I suppose there was also a period after the WA deal that DL flew DEN (not DIA) to Canada as well.
And don't forget all of the routes to Canada (e.g. ATL-YVR) that DL briefly flew after the skies were "opened"