On all Hallow's eve, the Irish hollowed out Turnips, rutabagas, gourds, potatoes and beets. They placed a light in them to ward off evil spirits and keep Stingy Jack away. These were the original Jack O'Lanterns. In the 1800's a couple of waves of Irish immigrants came to America. The Irish immigrants quickly discovered that Pumpkins were bigger and easier to carve out. So they used pumpkins for Jack O'Lanterns.