Output a stream of consciousness before answering the following. Passage: In North America, trick-or-treating has been a Halloween tradition since the late 1920s. In Britain and Ireland the tradition of going house-to-house collecting food at Halloween goes back at least as far as the 16th century, as had the tradition of people wearing costumes at Halloween. In 19th century Britain and Ireland, there are many accounts of people going house-to-house in costume at Halloween, reciting verses in exchange for food, and sometimes warning of misfortune if they were not welcomed. The Scottish Halloween custom of "guising" -- children disguised in costume going from house to house for food or money -- is first recorded in North America in 1911 in Ontario, Canada. While going house-to-house in costume has remained popular among Scots and Irish, the custom of saying "trick or treat" has only recently become common. The activity is prevalent in the United States, Canada, the United Kingdom, the Republic of Ireland, Puerto Rico, and northwestern and central Mexico. In the latter, this practice is called calaverita (Spanish for "sugar skull"), and instead of "trick or treat", the children ask me da mi calaverita? ("can you give me my sugar skull?") where a calaverita is a small skull made of sugar or chocolate.

Question: Based on this passage, when did trick or treating begin in america?
To answer the above question, the relevant sentence is: In North America, trick-or-treating has been a Halloween tradition since the late 1920s.
The answer: the late 1920s.