I've tried to write this post several times and I ran into the same problem every time - offending people. I've decided to take a totally different approach to this post and just talk about the stereotypes Americans have about each other and maybe touch on some of the language differences from region to region, basically a more lighthearted approach. Besides, without differences you can't have stereotypes.
I'll start with the Southerners, they're an easy target for a Yankee like me. They're slow - they speak slow, drive slow, talk slow - yup just slow. Ironically thought they seem to shorten terms - like saying Y'all. But at least the men are gentleman and the women ladies. They haven't gotten over the "War of Northern Aggression" - also known as the Civil War, which ended over 140 years ago! And then there is the issue of the inbreeding...
I hear that Northerners like to talk fast - it makes us a bit untrustworthy. Otherwise we're apparently pretty cool. But even within the North we have some issues. Like in Western Pennsylvania they call soda "pop" and use a "buggy" at the grocery store. They've got a wacky accent over in Massachusetts too, that's a whole different thing.
Out in the Mid-West are the polygamists, and the crazy militia people. And out in California the people are all fake and image obsessed, plastic surgeons do well here. And the call the West Coast the "Left Coast," not because it's on the left side of the country, but because all the liberals live there (well the ones who aren't in New York City.)
I hope I gave a little insight into how American's view each other and their cultural differences, assuming any of these stereotypes are actually true.