Folklore or fakelore, the general consensus seems to be that the Irish who came to America brought their custom of carving turnips for All Hallows Eve. They must grow large turnips in the sod over there! Lacking a turnip, rutabagas, beets, or gourds would also do.
Delicious legend, that’s what started the practice of carving Jack O’Lanterns, an example of how cultural practices migrate and are modified depending upon local conditions. Here’s the Tale of Stingy Jack:
© 2013 C. Bertelsen