London
There are many accents traditionally associated with London. The most well known of the London accents long ago acquired the Cockney label from London's East End, which is heard both in London itself, and across the wider South East England region more generally. The accent of a 21st-century Londoner varies widely; what is becoming more and more common amongst the under-30s however is some fusion of Cockney with a whole array of ethnic accents, in particular Caribbean, which form an accent labelled Multicultural London English (MLE). The other widely heard and spoken accent is RP (Received Pronunciation) in various forms, which can often be heard in the media and many of other traditional professions and beyond, although this accent is not limited to London and South East England, and can also be heard selectively throughout the whole UK amongst certain social groupings. Since the turn of the century the Cockney dialect is less common in the East End and has 'migrated' east to Havering and the county of Essex.
American English
American English varieties form a linguistic continuum of dialects more similar to each other than to English dialects of other countries, including some common pronunciations and other features found nationwide. Any North American English accent perceived as free of noticeably local, ethnic, or cultural markers is popularly called "General" or "Standard" American, a fairly uniform standard of broadcast mass media and the highly educated. Otherwise, according to Labov, with the major exception of Southern American English, regional accents throughout the country are not yielding to this standard, and historical and present linguistic evidence does not support the notion of there being one single "mainstream" American accent. On the contrary, the sound of American English continues to evolve, with some local accents disappearing, but several larger regional accents emerging.