While Halloween or at least the North American interpretation of it comes from the Celtic tradition of Samhain (Calan Gaeaf in Wales and Cornwall,) many cultures have their own variant of a holiday based around dressing up and perhaps going over to the neighbors to demand treats or songs.
In nearly all cases, these traditions had pagan roots, focusing on appeasing spirits, helping one survive winter and perhaps communicating with loved ones who had passed away. Post-Christianization, in many places, the church simply chose to “adopt” the ideas and shift them in a more “acceptable” direction.
At the time, the equivalent of a trick-or-treat was the practice of guising, where a group of children would dress up and go door to door in search of treats. The term “guising” comes from the dis-guises the children would wear. As many a curmudgeonly adult has said, children these days have it too easy. Back in the day, getting a treat from a house would require at least a verse or a song.
On the other hand, the guisers had more responsibilities as well. Trick-or-treat was taken more literally, where a lack of a treat would lead to tricks, or, in other words, mischief from the costumed children. These days, you are a lot less likely to encounter a child who will vent their fury at not getting some candy, unlike the guisers of the past.
The form of trick-or-treating, as we know it today, was first recorded in Kingston, Ontario, in 1911, where it looked much like the guising described earlier. In general, at the time there was a resurgence in interest around Halloween activities, as costume parties began to become more popular again.
American historian Ruth Edna Kelley wrote in 1919 that "The taste in Hallowe'en festivities now is to study old traditions and hold a Scotch party, using Burn's poem Hallowe'en as a guide; or to go a-souling as the English used. In short, no custom that was once honored at Hallowe'en is out of fashion now,” which with some minor modifications could be said to be true of today as well.
Soon after, the more common “trick-or-treat” demand emerged as standard. The Sault Daily Star, also based in Ontario, wrote that “Almost everywhere you went last night, particularly in the early part of the evening, you would meet gangs of youngsters out to celebrate. Some of them would have adopted various forms of "camouflage" such as masks, or would appear in long trousers and big hats or with long skirts.”
