The present study is a critical survey of dialectological and sociolinguistic studies, and should contribute towards answering the question whether dialect areas such as Boston and Eastern New England are converging or diverging. The study’s theoretical framework is based on both Lexical Diffusion and Neogrammarian positions. The pivotal Northern Cities Shift, a prominent and on-going vowel rotation pattern in the United States, the so-called «third dialect area», and «Boston English» are accommodated in the concepts of Lexical Diffusion and Neogrammarian viewpoints. The focal part is an empirical study investigating salient Bostonianisms (the short /a/, the short /o/, and the postvocalic /r/). Apart from theoretical considerations, the steps to run the VARBRUL program are explained and commented upon. Finally, the results of the study are discussed as they relate to social, regional and ethnic variations in North America.