Where do accents and dialects come from?
I have heard a lot about US and UK differences in spellings and their accents but then why are there differences? What's their origin?
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
Such difference in almost all the things (not only languages) arises due to various factors like Governing body, Media, culture of society etc. Wiki has an interesting article on these lines http://en.wikipedia.org/wiki/Comparison_of_American_and_British_English