In California, the vowels of KIT and DRESS may undergo lowering, and the vowel of TRAP may undergo both lowering and backing which results in realizations near [ε], [æ], and [a] respectively. Impressionistic descriptions of this trend suggest six sounds like sex, sex like sax, and sax like socks. This lowering appears to be a recent development and may be a change in progress. It was not noted in earlier studies of California English and seems to have come to the attention of linguists only in the mid-1980s. It is reported to be especially characteristic of the speech of young urban women—a pattern that is consistent with its interpretation as an active change. The geographical extent of this lowering is not known, but it has been documented in both Southern California and the San Francisco Bay area.

The behavior of the lax front vowels in California bears a striking resemblance to a pattern heard north of the border and known as the Canadian shift. Dialect contact is unlikely to be responsible for this similarity. Rather, the lowering in both varieties seems to stem from a common structural motivation. Both in California and across Canada, the LOT and THOUGHT vowels are merged, and, as described above, the resulting vowel is typically low and quite back. This merger thus provides /æ/ with greater freedom to shift since it can be lowered and retracted into the low central area of vowel space without encroaching on the territory of the LOT/THOUGHT vowel. When /æ/ shifts, this creates an opening into which /ε/ may be lowered, which in turns creates an opening into which /ɪ/ may lower. In this sense, the development of the lax vowels appears to be a chain shift, specifically a drag chain.