As Iowans prepare for trick-or-treaters, the history of Halloween has deep roots in agriculture. The fall slaughter of livestock is still a tradition in parts of Iowa. Ann Effland, the U.S. Department of Agriculture’s historical expert, says the practice of a fall slaughter dates back centuries and could be where some incorporated the idea of animal sacrifices on October 31st.

Effland says, “It may have developed from the practice of killing animals at the end of the harvest period to reduce the number of animals you’re going to feed and you can prepare your meat to be available throughout the winter.” Some of the ancient Celts in what’s now Ireland believed the spirits of people who recently died would roam the earth.

Effland says that may be where the custom of wearing frightening costumes originated. She says, “There’s some research that suggests that the dressing up was a way to scare them off.” October 31st was the last day of the calendar year for the Celts, Effland notes, and it signaled the end of the growing season and a looking ahead to winter.