Originally Posted by
CommuniK
I was also told by BA last time I tried that if I booked all the way through I wouldn't need to recheck.
Technically that is kind of correct a subtle way, in that you bag can and would be checked to the final destination - so the bag label would say LHR->SEA->PDX on it.
However, as is the case for any INT-INT or INT-DOM connection at any US airport (apart from MIA in certain cases) all checked bags must be collected at your first port of arrival and taken through customs. Once through typically there are re-check desks immediately after customs where you just bag drop and your bag will then go back in the system - no need for a new label as your existing label already covers the domestic connections.