Just the "inter" part of International.
As I've previously stated... An International Airport by definition, will have a Customs Office or Building on site to process any inbound International traffic, whether it be Commercial or Private. Airports like the Gerald R. Ford International Airport as well as the Buffalo Niagara International Airport do not currently have scheduled International flights for passengers (albeit the few seasonal charters) but are still "International" Airports due to them both having U.S. Customs on site to process flights (usually private jets) incoming from International destinations (for BUF and GRR, those are mainly flights clearing U.S. Customs coming in from Canada)
Same happened in SYR, its name is Hancock International Airport Still. They basically call all Airports international. We lost AC same time and before that no Canadian flights in over 25 years
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