Comment by nohat00

I call BS on the "don"/"dawn" isogloss on the SF peninsula. If it ever did exist, it certainly doesn't anymore. There are no cultural or social groupings along that isoglass that would justify how that line is shaped. Where your parents are from and your socioeconomic status to have way more influence on whether or not you have a "don"/"dawn" distinction than whether you are from San Mateo or San Carlos.