Now out: Volume V (the last) of The Dictionary of American Regional English (Sl – Z). Volume I came out in 1985, and the project goes back long before that. Now come digitization and indexing (and updating; see below); the lexicographer’s work is never done.
(Full disclosure: I’ve contributed material to DARE and also supported the project financially.)
Great stuff. Complete with maps of the distribution of the variants.
Note: the backbone of the work is the material collected by 80 field workers in 1965-70 (that is, over 40 years ago). The workers went to a assortment of sites spead more or less evenly across the U.S., interviewing people who’d lived in those places all their lives, favoring older informants and especially probing for old-fashioned words; this means that the interview data represent American English of about a century ago. (This collection scheme is similar to that of the American linguistic atlases, beginning with the Linguistic Atlas of New England (published 1939-43), which takes us back into the 19th century.)
The interviews had three parts (all recorded): a fixed questionnaire on specific lexical items; a reading of the “Arthur the Rat” passage, designed to give data on pronunciation; and free informal chat. This material was supplemented by extensive data from printed sources, from before the interviews and after. (Obviously, the supplemental material got more extensive as the volumes went on, so that the early parts of the alphabet can use some updating now.)