Midland American English is a regional dialect or super-dialect of American English, geographically lying between the traditionally-defined Northern and Southern United States. Many of the precise features and regional boundaries of Midland American English are in a state of transition, being revised and reduced by linguists due to definitional changes and several Midland sub-regions undergoing rapid and diverging pronunciation shifts since the mid-twentieth century onwards.
These general characteristics of the Midland regional accent are firmly established: fronting of the //, //, and // vowels occurs towards the center or even front of the mouth; the cot–caught merger is neither fully completed nor fully absent; and short-a tensing evidently occurs strongest before nasal consonants. The currently-documented core of the Midland dialect region spans from central Ohio at its eastern extreme to central Nebraska and Oklahoma City at its western extreme. Certain areas outside of this core also clearly demonstrate a Midland accent, including Charleston, South Carolina; the Texan cities of Abilene, Austin, and Corpus Christi; and central and southern Florida.
Twentieth-century dialectology was the first to identify the "Midland" as a region lexically distinct from the Northern and Southern U.S., later even focusing on an internal distinction (North Midland versus South Midland). However, twenty-first-century studies now reveal increasing unification of the South Midland with a larger, newer Southern accent region, while much of the North Midland arguably retains a more "General American" accent. Furthermore, since the early twentieth century, several Midland sub-regions have developed their own distinct dialects. Pennsylvania, the original home state of the Midland dialect, is one such area, having now formed such unique dialects as Philadelphia and Western Pennsylvania (Pittsburgh) English.
The dialect region "Midland" was first defined by Hans Kurath as centered on central Pennsylvania and expanding westward and southward to include most of Pennsylvania, and the Appalachian regions of Kentucky, Tennessee, and all of West Virginia. A decade later, Kurath split this into two discrete subdivisions: the "North Midland" beginning north of the Ohio River valley area and extending westward into Indiana, Illinois, Iowa, and northern Missouri, as well as parts of Nebraska and northern Kansas ; and the "South Midland", which extends south of the Ohio River and expands westward to include Kentucky, southern Indiana, southern Illinois, southern Missouri, Arkansas, southern Kansas, and Oklahoma, west of the Mississippi river. While Craig Carver and the related Dictionary of American Regional English based their 1960s research only on lexical (vocabulary) characteristics, William Labov and his team conversely based their 1990s research largely on phonological (sound) characteristics and defined the Midland area as a buffer zone between the Inland North and the South accent regions. In Labov et al.'s newer study, the "Midland" essentially coincides with Kurath's "North Midland", the "South Midland" being now considered as largely a portion, or the northern fringe, of the Southern dialect region. Indeed, while the lexical and grammatical isoglosses encompass the Appalachian Mountains regardless of the Ohio River, the phonological boundary fairly closely follows along the Ohio River itself.
The original Midland dialect region, thus, has split off into having more of a Southern accent in southern Appalachia, while, the second half of the twentieth century has seen the emergence of a unique Western Pennsylvania accent in northern Appalachia (centered on Pittsburgh) as well as a unique Philadelphia accent.
The dialect region of the Mid-Atlantic States—centered on Philadelphia, Pennsylvania; Baltimore, Maryland; and Wilmington, Delaware—falls under the Midland, except that it strongly resists the cot–caught merger and traditionally has a short-a split that is similar to New York City's, though still unique. Certain vocabulary is also specific to the Mid-Atlantic dialect, and particularly to its Philadelphia sub-dialect.
The emerging and expanding dialect of western and much of central Pennsylvania is, for many purposes, an extension of the South Midland; it is spoken also in Youngstown, Ohio, ten miles west of the state line, as well as Clarksburg, West Virginia. Like the Midland proper, the Western Pennsylvania accent features fronting of /oʊ/ and /aʊ/, as well as positive anymore. Its chief distinguishing features, however, also make it a separate dialect than the Midland one. These features include a completed LOT–THOUGHT merger to a rounded vowel, which also causes a chain shift that drags the STRUT vowel into the previous position of LOT. The Western Pennsylvania accent, lightheartedly known as "Pittsburghese", is perhaps best known for the monophthongization of MOUTH to PALM (/aʊ/ to [aː]), such as the stereotypical Pittsburgh pronunciation of downtown as dahntahn. Despite having a Northern accent in the first half of the 20th century, Erie, Pennsylvania, is the only major Northern city to change its affiliation to Midland by now using the Western Pennsylvania accent.
Today, the South Midland is an area with more Midland vocabulary and grammar but more Southern phonology. However, the South Midland employs some Southern vocabulary too, for example, favoring y'all as the plural of you, whereas the North Midland favors you guys.
Today, the city of Charleston, South Carolina, clearly has all the defining features of a mainstream Midland accent. The vowels // and // are extremely fronted, and yet not so not before //. Also, the older, more traditional Charleston accent was extremely "non-Southern" in sound (as well as being highly unique), spoken throughout the South Carolina and Georgia Lowcountry, but it mostly faded out of existence in the first half of twentieth century.
Older English speakers of Cincinnati, Ohio, have a phonological pattern quite distinct from the surrounding area (Boberg and Strassel 2000), while younger speakers now align to the general Midland accent. The older Cincinnati short-a system is unique in the Midland. While there is no evidence for a phonemic split, the phonetic conditioning of short-a in conservative Cincinnati speech is similar to and originates from that of New York City, with the raising environments including nasals (m, n, ŋ), voiceless fricatives (f, soft th, sh, s), and voiced stops (b, d, g). Weaker forms of this pattern are shown by speakers from nearby Dayton and Springfield. Boberg and Strassel (2000) reported that Cincinnati's traditional short-a system was giving way among younger speakers to a nasal system similar to those found elsewhere in the Midland and the West.
St. Louis, Missouri, is historically one among several (North) Midland cities, but it has developed some unique features of its own distinguishing it from the rest of the Midland. The area around St. Louis has been in dialectal transition throughout most of the 1900s until the present moment. The eldest generation of the area may exhibit a rapidly-declining merger of the phonemes /ɔr/ (as in for) and /ɑr/ (as in far) to the sound [ɒɹ], while leaving distinct /oʊr/ (as in four), thus being one of the few American accents to still resist the horse-hoarse merger (while also displaying the card-cord merger). This merger has led to jokes referring to "I farty-far", although a more accurate eye spelling would be "I farty-four". Also, some St. Louis speakers, again usually the oldest ones, have /eɪ/ instead of more typical /ɛ/ before /ʒ/—thus measure is pronounced /ˈmeɪʒ.ɚ/—and wash (as well as Washington) gains an /r/, becoming [wɒɻʃ] ("warsh").
Since the mid-1900s (namely, in speakers born from the 1920s to 1940s), however, a newer accent arose in a dialect "corridor" essentially following historic U.S. Route 66 in Illinois (now Interstate 55 in Illinois) from Chicago southwest to St. Louis. Speakers of this modern "St. Louis Corridor"—including St. Louis, Fairbury, and Springfield, Illinois—have gradually developed more features of the Inland North dialect, best recognized today as the Chicago accent. This twentieth-century St. Louis accent's separating quality from the rest of the Midland is its strong resistance to the cot–caught merger and the most advanced development of the Northern Cities Vowel Shift (NCS). In the twentieth century, Greater St. Louis therefore became a mix of Midland accents and Inland Northern (Chicago-like) accents.
Even more complicated, however, there is evidence that these Northern sound changes are reversing for the younger generations of speakers in the St. Louis area, who are re-embracing purely Midland-like accent features, though only at a regional level and therefore not including the aforementioned traditional features of the eldest generation. According to a UPenn study, the St. Louis Corridor's one-generation period of embracing the NCS was followed by the next generation's "retreat of NCS features from Route 66 and a slight increase of NCS off of Route 66", in turn followed by the most recent generations' decreasing evidence of the NCS until it disappears altogether among the youngest speakers. Thus, due to harboring two different dialects in the same geographic space, the "Corridor appears simultaneously as a single dialect area and two separate dialect areas".
Rather than a proper Southern accent, several cities in Texas can be better described as having a Midland accent, as they lack the "true" Southern accent's full // deletion and the oft-accompanying Southern Vowel Shift. Texan cities classifiable as such specifically include Abilene, Austin, and Corpus Christi. Austin, in particular, has been reported in some speakers to show the South Midland (but not the Southern) variant of // deletion mentioned above.