It is believed that Halloween originated from a Celtic holiday known as Samhain, which was celebrated in Ireland and Scotland at harvest time for well over a thousand years. Samhain was the time of year (October 31st) when harvesting was completed and animals were brought from summer pastures to shelter for the winter months. At Samhain a large festival was celebrated, and fruits, vegetables, grain, and animals, were burned as gifts to the gods in huge bonfires in hope of a successful new year. It was believed that during the night of Samhain, that the dead could walk among the living, and that the living could ask the dead questions about the future year. Because they believed some of these spirits were evil, they wore costumes with animal heads to scare the spirits and protect themselves.

Christianity spread to the Celtic lands, and in the seventh century, Pope Boniface IV declared November 1st to be All Saints Day, otherwise known as "All Hallow's Day," hallow referring to sainted ones. All Saint's Day was to celebrate the holy saints and martyrs of Christianity. It is generally believed that this was an attempt to Christianize the popular Celtic holiday and diminish the importance of the Celtic ritual and the influence of their spiritual leaders, the druids. This is also how the day became known as All Hallow's Eve, or Halloween. All Soul's Day was similarly added in Christianity a couple hundred years later to celebrate the dead.

Carving out turnips and lighting them goes back hundreds of years with the holiday. An Irish legend tells of a man named Jack who tricks the devil to turn into a coin and keeps him from changing back by placing the coin next to a cross. A year later, Jack dies, but is neither allowed into heaven, or hell, so he must roam the earth. The 1800's brought Halloween to the United States with the Irish immigrants. Pumpkins were carved rather than turnips because they were large and more plentiful.