FTM's arrival and departure tags are not supported by GEDCOM. It only supports EMIG and IMMI. If you read the definitions, these are both in reference to intent for permanent residence. That leaves a gap in there for using departure and arrival tags to capture events that don't pertain to intent to permanently reside somewhere. If I recall, in the past, FTM used to export these with its own custom tags (that didn't include an _ *tsk tsk), but I think they cleaned it up in the GEDCOM to make it more compliant. I believe now that "arrival" is specified as an event type in the GEDCOM, but I haven't looked at an export in a while to be sure.
From a GEDCOM perspective, EMIG and IMMI are not limited to countries. These tags should be used with any location.
EDIT: I change every "arrival" fact auto-generated from census records. I convert them all to IMMI. That was the question asked on all the census, and that's the right tag, whatever your opinion is on the question of arrival vs. immigration.