Midland American English

Midland American English is, historically, a regional dialect or super-dialect of American English, and, currently, a related set of English varieties in transition, geographically lying between the traditional Northern and Southern United States. Its exact regional boundaries and defining features are somewhat debated among linguists due to its pronunciation undergoing rapid changes since the mid-twentieth century. These general characteristics of the Midland accent are firmly established: fronting of the /oʊ/, /aʊ/, and /ʌ/ 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 southeastern Nebraska and Oklahoma City at its western extreme. Certain cities outside of this core also clearly demonstrate the Midland accent, including Charleston, South Carolina; Abilene, Austin, Corpus Christi, and perhaps El Paso, Texas; and the cities of central and southern Florida.

The North Midland accent arguably falls under the umbrella of General American, or is even becoming the "default" for a General American system; however, South Midland pronunciation demonstrates more of the character of a Southern accent, with a variably "glideless" /aɪ/ vowel (reminiscent of the Southern U.S. accent, but only appearing before sonorant consonants) and an extremely fronted /oʊ/ vowel. Early twentieth-century boundaries established for the Midland dialect region are being reduced or revised, since several previous sub-regions of Midland speech have since 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 Pittsburgh English.

...
Wikipedia