This study examines cross-generational changes in the vowel systems in central Ohio, southeastern Wisconsin, and western North Carolina. Speech samples from 239 speakers, males and females, were divided into three age groups: grandparents (66–91 years old), parents (35–51), and children (8–12). Acoustic analysis of vowel dynamics (i.e., formant movement) was undertaken to explore variation in the amount of spectral change for each vowel. A robust set of cross-generational changes in /ɪ, ɛ, æ, ɑ/ was found within each dialect-specific vowel system, involving both their positions and dynamics. With each successive generation, /ɪ, ɛ, æ/ become increasingly monophthongized and /ɑ/ is diphthongized in children. These changes correspond to a general anticlockwise parallel rotation of vowels (with some exceptions in /ɪ/ and /ɛ/). Given the widespread occurrence of these parallel chainlike changes, we term this development the “North American Shift,” which conforms to the general principles of chain shifting formulated by Labov (1994) and others.