The Western dialect of American English is a single regional English dialect that largely unites the entire western half of the United States, including California, Nevada, Arizona, Utah, New Mexico, Colorado, and Wyoming. It also broadly encompasses Washington, Oregon, Idaho, and Montana, which are sometimes separated into their own Pacific Northwest sub-dialect. The west was the last area in the United States to be reached during the gradual westward expansion of English-speaking settlement and its history shows considerable mixing of the linguistic patterns of other regions. As the settlement populations are relatively young when compared with other regions, Western American English is a dialect area in formation.
buckaroo: cowboy. Originating in California, it is an Anglicization of the Mexican vaquero; the corresponding term which originated in Texas is "wrangler" or "horse wrangler", itself an Anglicization of the Mexican caballerango.
gunnysack as opposed to burlap bag (the latter more common east of the Mississippi)
shivaree as opposed to belling or serenade ("shivaree" is the more common usage east of the Mississippi and in Kentucky and Tennessee; "belling" is the more common usage in Ohio, while "serenade" is the more common usage in Atlantic states—except New York and Connecticut—and the Appalachians)
like in Canada and much of the Midland, /ɑ/ allophones may be either rounded or unrounded due to a lack of phonemic distinction between [ɑ] (listen) and [ɒ] (listen), and these are further back than in the Great Lakes.
Unlike the Highland South, /oʊ/ is conservative (little fronting) and the cot–caught merger is complete (except in San Francisco).
But /u/ is being fronted like in most of North America.