As someone who used to travel between the US and Canada frequently, I always found whatever partnership existed between AC and UA to be essentially worthless from a passenger’s perspective. The announcement made last year, for the most part, amounted to the partnership remaining almost as worthless as it’s historically been.

The one thing they could have announced that would be of real benefit is transborder baggage forwarding in Canada on UA/AC connections. AC does this at their hubs with customs handled virtually (similar to how customs works at US preclearance airports) so why can’t UA and AC figure out how to do it on interlined bags?