More people, especially millennials, are buying costumes for their pets. Twenty percent did so in 2018, up from 16 percent in 2017. 

One quarter of all the candy sold annually in the U.S. is purchased for Halloween.

The American Halloween tradition of trick-or-treating probably dates back to the early All Souls’ Day parades in England. During the festivities, poor citizens would beg for food and families would give them pastries called “soul cakes” in return for their promise to pray for the family’s dead relatives. The distribution of soul cakes was encouraged by the church as a way to replace the ancient practice of leaving food and wine for roaming spirits. The practice, which was referred to as “going a-souling,” was eventually taken up by children who would visit the houses in their neighborhood and be given ale, food and money.

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” tradition. Young women believed that on Halloween they could divine the name or appearance of their future husband by doing tricks with yarn, apple parings or mirrors. In the late 1800s, there was a move in America to mold Halloween into a holiday more about community and neighborly get-togethers than about ghosts, pranks and witchcraft. At the turn of the century, Halloween parties for both children and adults became the most common way to celebrate the day. Parties focused on games, foods of the season and festive costumes. Parents were encouraged by newspapers and community leaders to take anything “frightening” or “grotesque” out of Halloween celebrations. Because of these efforts, Halloween lost most of its superstitious and religious overtones by the beginning of the twentieth century. (History.com)

(history.com).