Low back merger in the context of "Dialects of English"

Western American English (also known as Western U.S. English) is a variety of American English that largely unites the entire Western United States as a single dialect region, including the states of California, Nevada, Arizona, Utah, New Mexico, Colorado, Wyoming, and Montana. It also generally encompasses Washington, Oregon, and Idaho, some of whose speakers are classified under Pacific Northwest English.

The West was the last area in the United States to be reached during the gradual westward expansion of settlement by English speakers and its history shows considerable mixing and leveling of the linguistic patterns of other regions. Therefore, since the settlement populations are relatively young when compared with other regions, the American West continues to be a dialect region in formation. According to the 2006 Atlas of North American English, as a very broad generalization, Western U.S. accents are differentiated from Southern U.S. accents in maintaining /aɪ/ as a diphthong, from Northern U.S. accents by fronting /u/ (the GOOSE vowel), and from both by consistently showing the low back merger (the merger of the vowel sounds in words like cot and caught). Furthermore, in speakers born from the 1980s onward, the related low-back-merger shift has been spreading throughout the Western States, as well as throughout the entire United States. The standard Canadian accent also aligns with these defining features, though it typically includes certain additional vowel differences.

The Low-Back-Merger Shift is a chain shift of vowel sounds found in several accents of North American English, beginning in the last quarter of the 20th century and most significantly involving the low back merger (which collapses together the low-back vowel sounds: /ɑː/, /ɒ/, and /ɔː/ in words like PALM, LOT, and THOUGHT respectively) accompanied by the lowering and backing of each of the front-lax vowels: /æ/, /ɛ/, and /ɪ/ (in words like TRAP, DRESS, and KIT respectively).

The back and downward movement of all the front lax vowels was first noted as distinguishing certain California English speakers in 1987, and it was soon known by linguists as the California Vowel Shift. Then, it came to distinguish certain Canadian English speakers in a 1995 study, now known in that variety as the Canadian Shift; today, it helps define Standard Canadian English. The California and Canadian Shifts were initially reported as two separate phenomena, but the same basic pattern was next documented among some younger varieties of Western New England English, Western American English, Pacific Northwest English, and Midland American English, all in speakers born from the 1980s onward. Linguists have proposed possible relationships between the low back merger and the similarly structured shifts in these regional dialects, though no unifying hypothesis is dominantly agreed upon yet. Assuming the similar chain shifts found in Canada and various parts of the U.S. have a single common origin, a variety of names have been proposed for this trans-regional chain shift which, besides the low-back-merger shift, include the Third Dialect Shift, Elsewhere Shift, Short Front Vowel Shift, and North American Shift.