Low back merger
Pittsburgh dad: giving directionsPlay video
This video comes from a channel dedicated to this character of "the Pittsburgh dad". This is what people usually think of when they think of a Pittsburgher in terms of accent and slang usage. Many Pittsburgh natives don't necessarily talk like this, though many do to varying degrees, so the accent indexes this persona more-so than it does the concept of localness. There are tons of other videos on the channel, but I think this one shows a lot of examples of the low back merger.
Fargo - Chit ChatPlay video
Having experiences traveling around the country, many people find Minnesotan accents to be a novelty. In this clip from the movie "Fargo", two Minnesotan men are discussing a recent homicide in the town. The example does a great job of portraying the conversational mannerisms and (overwhelmingly polite, questioning, not all that descriptive, and full of town references) that one finds in Minnesota, North Dakota, and Wisconsin.
Fast Times at Ridgemont High (2/10) Movie CLIP - Spicoli Meets Mr. Hand (1982) HDPlay video
Examples of the third dialect in the 1982 movie Fast Times at Ridgemont High.
In Walsh, students of Bostonese have found their avatah
A 2013 article on Boston mayor-elect Marty Walsh, who has a pronounced Boston accent. The comments about Boston being "lazy" are unfortunate, as are the interviews with speech coaches.
Trailer Park BoysPlay video
A scene from the Canadian mockumentary "Trailer Park Boys."
Quiz: What American accent do you have?
A short quiz that identifies your American accent, using criteria like low-back merger, pin-pen merger, and the Mary-merry-marry distinction.
A scene from the movie Fargo, where actors use exagerrated Northern accents.