CHICOPEE, Mass. (WWLP) — Sunday night is the night when little ghouls, goblins, and witches will come to your front door, looking for a smile and a little bit of candy. But how and where did this tradition begin?

Halloween’s origins date back to the ancient Celtic festival of Samhain. The Celts lived 2,000 years ago and mostly in the area that is now Ireland, the United Kingdom, and northern France. They celebrated their new year on November 1. This day marked the end of summer and the harvest and the beginning of the dark, cold winter, a time of year that was often associated with human death.

Celts believed that on the night before the new year the boundary between the worlds of the living and the dead became blurred. On the night of October 31, they celebrated Samhain when it was believed that the ghosts of the dead returned to earth. During the celebration, the Celts wore costumes typically consisting of animal heads and skins and attempted to tell each other’s fortunes.

Fast forward 1900 years and in the second half of the 19th century, America was flooded with new immigrants. These new immigrants, especially the millions of Irish fleeing the Irish Potato Famine, helped to popularize the celebration of Halloween nationally. Borrowing from European traditions, Americans began to dress up in costumes and go house to house asking for food or money, a practice that eventually became today’s “trick-or-treat.”

Thus, a new American tradition was born, and it has continued to grow. Today, Americans will spend an estimated $10 billion annually on Halloween, making it the country’s second largest commercial holiday after Christmas.