Virtually everything is interconnected [0], but some regions are more connected than others. All the producers and consumers know how much it costs to ship to/from different hubs, including Asia and Europe, and will do so very quickly whenever it becomes economic.
As you can probably tell from the wikipedia graph, the gulf is heavily plumbed. In addition to the shipping and processing in the gulf, there are also massive storage caverns [1] that can buffer most swings in demand. Different US regions have their own storage hubs [2] but the reason that lots of natural gas-related prices have "Mont Belvieu" in the name is that Mont Belvieu TX is basically the biggest storage hub and serves as the benchmark for everyone else.
