On charts for ships in international trade coming in to the US, look for the COLREGS demarcation line. Also, that’s another reason to have the local knowledge you get from a pilot being on board.
In the Inland Rules themselves it gives you the areas as well.
Yes, “See you on the one” is shorthand that can cause confusion for those not used to it, but you can always ask them to clarify if your faced with a term your not used to.