You would think that after 60+ years that I would comfortably remember which spelling of for the past tense of ‘cancel’ was the common American English version and which was British English version. When it comes to a few words that I stumble over, I still need to check with Merriam-Webster.
British vs. American English
Another fine example that has answers of varying degrees of complexity is the question of how many Ls one should use in the past or present participle form of the verb cancel. The simple answer to the question of ‘is it canceled or cancelled’ is “either one is fine.”
Now for the less simple answer. Canceled and canceling are more common in the US, while cancelled and cancelling are more common in British English. As explained by Lynne Murphy, American and British English have many similar habits when it comes to past and present participles: both double the final consonant of a word when it follows a short vowel and has the stress on the syllable attached to the suffix (such as remit/remitted/remitting). However, if the stress does not come on the syllable that attaches to the suffix then the final consonant is not doubled (as is the case with edit/edited/editing).
Origin of Single-L 'Canceled'
It is easy, as with the case of many of the words which are spelled differently in the US, to place the blame/credit with Noah Webster. However, while Webster’s early 19th century dictionaries helped solidify many of the spelling differences between these forms of English, in most cases he was simply making note of an orthographic variation that already existed. Webster’s 1806 dictionary has cancelled, but in his 1828 the word is spelled as canceled.
There are examples of cancelled in American use, and of canceled in British, so you needn’t feel bad about yourself if you mistakenly use the variant that is less common where you live. And if you still feel bad about your spelling allow us to give you some comforting words on the subject, taken from the Merriam-Webster Dictionary of English Usage: “Our present-day spelling, then, is a mishmash of archaism, reform, error, and accident, and it is unsurprising that not everyone who is heir to the tradition can handle it perfectly.