To be green means many things today (sustainable, energy conscious, eco-aware) but for immigrants new to America in the early 20th century it meant untested, even ignorant. (There was little, if any compassion for a “newbie”—no orientation or “onboarding”.) Green meant innocent, unproven—and on the rocky voyage over from Ireland, it also meant unwell. 

To lose one’s “greenness” was thus both a badge of honor, and a symbol, however problematic, of assimilation.