If I understand correctly, if your airplane or boat arrived on Shabbos, you're stuck within a ~half-mile radius of the boat or plane until after Shabbos because of techum. (I'd heard some discussion about how Ben Gurion Airport is set up for this situation?)
I assume theoretically the same would apply to those who arrived at Ellis Island on Shabbos, which I'm sure happened. Do we have any written sources that specifically discuss immigrants arriving at Ellis Island vis-a-vis the halachos of techum on Shabbos? Could be anything from a halacha sefer to a random newspaper article reporting on the predicament.