Originally Posted by
FlyingHoustonian
I fly this often.
A passport will make your life much easier sine Guam has its own customs union and a separate VWP and entry requirements. At the gate flying to HNL CBP sets up and processes you right as you come up for boarding.
How does the CBP verify that someone is a genuine US citizen? (not a
Canadian posing as one)
I assume it's pretty easy to verify foreign visitors and naturalized US citizens
and green card holders, since these three groups of folks must still have their
personal data and fingerprints stored somewhere within the CBP/USCIS
computer somewhere.