How did it come about that so many English words are spelled differently by Americans?

Yes, as in the Webster stuff ... though not sure about words that are spelled and pronounced differently like :

UK: Aluminium

US: Aluminum

As the rest of the corresponding elements have the ending -ium, why should this one be different?

English spelling was still very idiosyncratic, darling, and very much a matter of individual pronunciation and practice when America was being settled. Before universal public education became the norm, how people spelled some words, the patterns of spelling they used, depended, to a large extent, on how they pronounced (and spelled out) words, and the practices of the person who taught them to spell. People often used a number of variant spellings - often in the same work, and sometimes on the same page - and were, to our eyes, remarkably casual about how to spell.

It is only very recently (in terms of the history of the language) that standardized spelling became a real issue, and some very prominent people called for a serious effort to be made to regularize and standardize spelling - for example, in the UK, George Bernard Shaw was a passionate advocate of spelling reform, as was Noah Webster, here in the US.

From the mid-nineteenth century onward, these spelling reform efforts resulted in the textbooks and prescriptive dictionaries used in classrooms on both sides of the Atlantic, and different choices (that depended on the particular spelling fads followed by the writers) were imposed on schoolchildren in each country.

In England, spelling instruction tended to focus on regularizing, rather than reforming, and the most common and widespread spelling variants were often accepted over newer, "reformed" or modern variants. Spelling differences between homonyms such as "flower" and "flour" were standardized for clarity, and regional differences in spelling were resolved.

In the US, Webster and others argued passionately for reform, insisting that extraneous letters, such as the "u" in honour and neighbour, should be dropped, that z more accurately reflected the final siblant sound in "realise," and other things that we in the States now take for granted in our spelling. Webster himself had other ideas that were less accepted - he proposed that a group of adult female humans should be spelled "wimmen," for example - but many were, and we continue to use them today.

(((Nikon)))

two things come to mind, first, americans come from so many different nationalities, and I think that this has an impact on the language, both in terms of how we pronounce words and to a lesser extent the spelling, German is actually the biggest single nationality that white americans come from, I am not sure, but maybe a somewhat German style affects us? and of course spanish is an increasingly big influence and is creeping into american english, we use Yiddish more than Brits as well (just a sprinkling of a few words).

part of it is just the natural drift of style over time, in most cases England probably uses the language more "correctly" to the original style, but I bet there are even some cases where Americans use a word more like its original intent than in Britain, just as a chance of how language evolved differently.

Search for the Simplified Spelling Board on Google. They were set up by some guy called Carnegie in (I think) 1906.... anyway this guy had a real thing against certain spellings. Most of his ideas were ignored and forgotten, but some caught on (colour-color, catalogue-catalog, programme-program, mould-mold etc etc.)

I dunno

But I know a lot of words both English and Yank that are the spelled same with entirely different meanings and pronunciation.

RScott

After the Revolutionary war, America wanted to be as different from England as possible.So, they changed the spelling of some words.This also explains why people drive on different sides of the road in those different countries

The Webster(Noah, I Googled it) that wrote the first American dictionary revised most of the English words to his liking. He deliberately made it different than English usage. True.

Americans realized the "u" in words like honour and colour were useless so they dropped them but the English never did.

Well Americans saw that "zee" was a letter that was really missing out, and that English speakers and speller were not using it to its full potential. For realz!

cu wer lazy.... lol yea thats kinda y :PPP