Just after the Revolution, there was a movement among the Jefferson-Franklin crowd to Americanize spelling. I'm sure they would have wanted to come up with an entirely new language if they thought it possible. Changing the spelling was the next best thing. The differences in US/UK spelling are the result, most notably -or/-our and check/cheque. They were so "enlightened," donchaknow.
I was the county spelling champion when I was in the eighth grade (13 years old). I won with "canceled"; I lost the district contest, spelling "rhythm" as "rhythem."
I used to be a pretty good speller, but thirty years of reeding studint papers has pritty mutch ruined that.