Halloween originated over 2000 years ago among Celtic populations in Ireland, England, and France who celebrated Samhain at the end of harvest season. They believed spirits of the dead returned to Earth and people wore costumes to avoid being recognized as spirits. The Christian church influenced Halloween traditions by establishing All Saints' Day on November 1st, and people began participating in trick-or-treating, going door-to-door for food and money. Halloween traditions spread to America in the 1800s through Irish immigrants and incorporated the use of pumpkins instead of turnips for jack-o-lanterns.