20 years ago then-INS (now CBP) at PDX had a terrible reputation for Asia flights with a much higher rejection rate than other west coast airports. Obviously lots of time has passed (and one would hope conduct has improved) but could still be a non-zero factor for non-PDX-originating customers - all else being equal why deal with potential drama.

Link: https://www.washingtonpost.com/archi...-ed7f1b79976c/