Speaking accents and speaking pattern in the US

I have some questions on speaking accents and speaking pattern in the US.

1 How did Americans lose the British accent.

2 Where did Americans pick up all those other accents at one time it was just southern US accent and Boston and New York accent now we got south west accent and north west accent.:o:o

3 Why did people in the NON southern states started to talk very fast
Good video fast talker

More in-between two

Bit slower

Note it is hard to find videos on youtube of slow or fast talking only thing is to search by video blog.

Could it more relax culture talk slower and jobs that every minute talking was money people started to talk faster?

4 Why do media and broadcaster talk so fast.And was it always like this? Some people here say there where schooled in midwest or new York ? Could that be why?

When most Hollywood movies are bit slower talking.