When flying PVG -> YVR -> PDX (all on AC), I thought one was required to reclaim checked luggaage in YVR in order to clear US Customs. However the YVR website says this is not required. Does anyone know how it really works?

From the site:
"Most passengers will have their luggage checked-through to their final destination, so you will not claim your checked-bags at YVR."

nrgiii