I'm going to arrive at IAH on United from PTY, clear U.S. Customs, and then connect on Air Canada to YYC.

I'm concerned about connection time in IAH... I'll need to clear U.S. Customs, which may take some time (even though I'm Nexus/GT). And UA Intl flights arrive IAH Terminal E, while AC flights depart all the way over in Terminal A.

My checked baggage will be tagged by United at origin, and will be tagged all the way through to YYC. I'll obviously have to claim them while clearing U.S. Customs.

Once I clear Customs in Houston,

• can I drop my bags again with UA (at their connection desk inside Customs)?
• Or is there a generic "all airlines" baggage drop there for connecting passengers whose bags are checked to another destination?
• Or will I need to haul all of my luggage on that little train that connects terminals, find the Air Canada check-in counter in Terminal A, and drop my checked baggage with AC there?

(Family trip, so we're unfortunately traveling 'heavy'. No chance to do carry-on only on this one in order to speed us up! And, since our outbound from IAH is on AC, we can't get TSA Pre-Check fast lane access. It will be slow lane security once we get to Term A.)