ShotOne - I see the problem. A question now. Could British registered A/C use ORD as a hub, and fly to Canada and Mexico, for instance?
Cruise ships of practically every nation use US Ports to go all over and back. The only cruise ships left in US Registry are in Hawaii. We've cruised to Bermuda from NY on ships registered in Norway, and Liberia (what a joke!). Foreign ships cruise the inland waterway to Alaska from Vancouver, BC, and from Los Angeles to Mexican ports.