These are the maps from my poster presentation at NWAV 33 in Ann Arbor, Mich., on 1 October 2004:
Map 1, showing the distribution of tense/lax
neutralization (TLN) in the Linguistic Atlas of New England.
Map 2, comparing the TLN isogloss to the boundary between the Eastern and Western New England settlement regions.
Map 3, showing the monophthongization of /ehr/.
Map 4, showing the distribution of rhoticity (and the East/West boundary).
Map 5, comparing the TLN isogloss to the combination of the isoglosses from Maps 3 and 4.
Here's the handout that went with my poster and describes my methodology, in PDF form.
LANE: Linguistic Atlas of New England, vol. 2, 1941. Ed. Hans Kurath. Providence: Brown University; and Kurath, Hans, Handbook of the Linguistic Geography of New England, 1939. Providence: Brown University.
Nagy, Naomi, 2001. "'Live Free or Die' as a Linguistic Principle". American Speech 76:30–41.
Wells, J.C., 1990. "Syllabification and Allophony" in Susan Ramsaran (ed.) Studies in the Pronunciation of English: A Commemorative Volume in Honor of A.C. Gimson, 76–86. London and New York, Routledge.