Originally Posted by HkCaGu

HNL-GUM-SPN: Arriving at GUM, just follow the connection sign and proceed to your next gate. Arriving at SPN, you go through CNMI customs.

SPN-GUM-HNL: Before boarding at SPN, UScBP conducts a gate area document check for Guam admissibility. Before boarding at GUM, you have to pass a UScBP counter to get inspected for stateside admissibility. When you get off at HNL, you will proceed directly to baggage claim followed by a USCbp customs inspection.