The sociolinguist William Labov has worked for decades on change in progress in American dialects and on African American Vernacular English (AAVE). In Dialect Diversity in America, Labov examines the diversity among American dialects and presents the counterintuitive finding that geographically localized dialects of North American English are increasingly diverging from one another over time. Contrary to the general expectation that mass culture would diminish regional differences, the dialects of Los Angeles, Dallas, Chicago, Birmingham, Buffalo, Philadelphia, and New York are now more different from each other than they were a hundred years ago. Equally significant is Labov's finding that AAVE does not map with the geography and timing of changes in other dialects. The home dialect of most African American speakers has developed a grammar that is more and more different from that of the white mainstream dialects in the major cities studied and yet highly homogeneous throughout the