How did the Americans learn to spell English differently from the British? Why did 'lustre' become 'luster'? And, why, for that matter, didn't 'grotesque' become 'grotesk'?
How, in other words, did American English and British English grow apart? This animated video has some answers.
We’re lucky in our modern-day habits because we can turn to the dictionary when in doubt about a spelling. When the pilgrims left for what were to be the American colonies, they had books but not dictionaries. And publishers weren't all that rigid about spelling at the time.
In 1755 Samuel Johnson tried to standardise things with A Dictionary of the English. But America got its own Johnson only in 1806, in the form of Noah Webster, who thought that the new country "should be as independent in literature as she is in politics".
Exit all letters not pronounced, such as the "u" in "colour" or "odour". Enter "er" instead of "re", like in "centre/center" to be consistent with pronunciation. Out with the "c" when the sound was of an "s", such as "offence/offense".
All of which has, of course, only added to spellcheck and autocorrect nightmares today.