Umm, sort-of. I have relatives whose local dialect is almost incomprensible to me. (They can understand me because they can understand "TV American".)
> Compare that to Europe where there are, what ? 23 languages for 27 countries
How many of them have a significant number of people who are monolingual? To put it another way, how many languages do I need to know to talk to 95% of Europeans?
> the newspapers are the same,
No, they aren't.
> the political parties are the same.
Nope. They merely have the same names, and sometimes not even that. (see http://en.wikipedia.org/wiki/Minnesota_Democratic%E2%80%93Fa... .)
Yes, there is a national Democrat party, but there are also 50 state parties and they don't take orders.
There are "national coalitions" that don't cover all states.