Long ago in grade school we were taught the correct spelling WAS "Cancelled." When did they (spelling police?) decide it is "Canceled?" Personally drives me nuts. I dislike flying and try to avoid it. Being at a airport during heavy thunderstorms and seeing every board with flights that are "Canceled" trips my OCD. Spelling differences between US & UK, however, I find interesting.
In American English, the verb cancel is usually inflected canceled and canceling—with one l. This is not a rule, however, and exceptions are easily found. In varieties of English from outside the U.S., including Canadian, British, and Australian English, cancelled and cancelling are the preferred spellings.
The spelling distinction extends to cancelers and cancellers, as well as to cancelable and cancellable, but it does not not extend to cancellation, which everywhere is spelled with two l’s.