Originally Posted by
federernadal
Then in Seattle, when the immigration officer will check me, I will need to open the bags in front of him, where he will check. Then he will say OK and I'm guessing he will put some OK stamp on my bag which will waive any checking later on in Denver/Montana. This sounds right I guess. What do you say?
No. That does not sound like the regular procedure. IF your bag is opened it will be done out of your sight after both immigration and customs in preparation for your bag to be loaded on a domestic flight.
Just put everything of value in your carry-on. If you don't have a so-called TSA-approved lock, just secure your zipper with a plastic or metallic or rubber tie to keep it together.
Or you can have your bag locked during the international flight and take away the lock when you temporarily meet your luggage at SEA, but it's not really worth the trouble.