There are distinct accents in the North and in the South.
As someone who talks for a living, I can assure you practically every region of the US has some form of 'accent'.
Boston is easy: "It's not faaahhh to the caaah" (although as a native, I can tell you most most exagerations are way overboard.) Believe it or not, the accents found in and around New Orleans are strangely similar to Boston.
New York has a variety of different accents and -isms. One that New York and New Jersey-ites rarely catch though is how they can turn "st" into "sch"..
EX: I'm driving schtraight to Philly. Another New Jersey -ism is the ability to trail off when a word ends in a "ton.." Down here there's a town called Boynton Beach, and everyone I know from Jersey pronounces it "Boyn-un" The "t" dissapeers.
The accent gets unique around Philly and Baltimore too. The vowels get stretched almost midwestern-style...in fact at Camden Yards in Baltimore, they have a tradition of adding a local touch to the national anthem..."Oh Say Does that Star...." becomes, in the local dialect, a stretched O, almost ending in a "U" sound.
I'd break southern accents down into Geor-gyah...and everywhere else.
The midwest accent starts in western New York, with a noticable Bronx flavor and , like pizza, goes Chicago style the closer to the windy city you get. Perfect Chicago accent? (Sorry, Chi-caw-go accent): Elwood Blues.."you waaahnt I should wipe da bugz ahhfff the windshield?"
Michigan is, if you look at the state, essentially an island. Nobody drives "through" Michigan to get from one part off the country to the other. That means the dialect has evolved on it's own. A man from Michigan will "gwan dow-en to Mejers to buy some haaahm-burg." Then insist he has no accent.
Texas is half-Midwest, half south. Nothing more complicated than that. Texans will tell you God invented their accent and speaks with it, but I'm afraid its just a meeting of two seperate regions. "Y'all" sounds like a word that is more comfy over east of Texarkana. But Texans can claim "fixin'" all to their own (I'm fixin' to go pee). After all, who would want it. (
Climb along the Rockies and you'll probably find an area closest to accent-free as there is. I don't know any particular -isms about the area, except "Go Buffs" for that scumsucking pagan college football team of theirs.
I'm kind of in the dark about out West. I've noticed the aforementioned Pennsylvania sound out around Utah. California has picked up on surfer and military lingo ("dude" "rad" "outstanding"), but again I havent lived out West so I'm not sure there's any noticable accent.