The Celtic festival of Samhain (sow-in) in the UK, Ireland and northern France celebrated the new year on November 1-worlds between living and dead were thought to be blurred, with ghosts returning to earth on October 31. Celtic priests, Druids, built sacred bonfires and Celts wore costumes so that the roaming ghosts could not recognize them.
The Romans, who conquered most of the Celtic territory by 43 A.D., combined two of their festivals with with Samhain. With Feralia, in late October, the Romans honored the dead. The festival for Pomona, the Roman goddess of fruit and trees, was symbolized by an apple (perhaps the origin of our bobbing for apples).
Pope Gregory III in the mid 700’s expanded All Martyrs Day to include all saints as well as martyrs and moved the observance from Pope Boniface’s original May 13 date (609 A.D.) to November 1. In 1000 A.D., November 2 was made All Souls Day, perhaps to replace the Celtic holiday. The celebration was also called All-hallowsmas (from Middle English for All Saints Day) and the night before, the old Samhain, came to be called All-hallows Eve…eventually, Halloween.
In America, Halloween was originally celebrated in the south. The harvest was celebrated with neighbors; stories of the dead were shared; and dancing, singing and mischief were common. After large waves of immigration in the mid-1800’s, especially with the Irish, the celebration spread to the north; people dressed in costumes and began going door-to-door asking for food or money.
By the 1920’s or so, the celebration became secular and mischief was discouraged by providing neighborhood children with treats; treats also originated with the English custom of giving poorer citizens pastries called “soul cakes” during All-Hallows Day festivities in exchange for their praying for the dead of the givers and that is the history of Halloween.