William Labov. 1997. The social stratification of (r) in New York City
department stores. Coupland, Nikolas and Adam Jaworski
eds. Sociolinguistics: A reader and coursebook. pp. 168-78. This is a
shortened version of the paper appearing in Labov
(1972). Sociolinguistic
patterns. Philadelphia, University of Pennsylvania Press.
( .pdf file)
Labov's short NPR interview about social variation in New York City
speech here is a
great accompaniment to this paper.
Visit maps of North American English, most
particularly the
National
Map
of the Regional Dialects of American English. The maps on this
site show the main vowel shifts that characterize the major regional
dialects.
The real thing is available on CD-Rom in Green Library:
William Labov, Sharon Ash and Charles
Boberg. 2006. The atlas of North American English : phonetics,
phonology, and sound change : a multimedia reference tool. Berlin ;
New York : Mouton de Gruyter.
The American Dialect Society has a page with a bunch of
links
(many of
them dead...) to sites dealing with American dialects.