Folk speech refers to the dialect, or style of speaking, unique to people living within a geographic area. The folk speech of an area may be differentiated from other regions by variation in grammatical, phonetic (pronunciation), and lexical (word usage) features. Along with other forms of traditional culture, such as music, dance, and folklore, folk speech plays a role in the conservation and perpetuation of Great Plains culture.

In his book (1931), Walter Prescott Webb noted that sign language was an essential early form of communication in the Great Plains. Using hand and arm gestures, sign language made intertribal communication possible among Plains Indians. Subsequently, the westward movement of European Americans during the nineteenth century established the basic geographical patterns of speech within the Great Plains that persist to this day. Because of the area's relatively recent settlement (by non-Indians), migration patterns played a more immediate role in influencing contemporary patterns of speech within the Great Plains than in many other parts of North America.

Characterizing the folk speech of the Great Plains presents a significant challenge because the region is a meeting place of several migration streams. Another difficulty is determining what set of words, pronunciations, and grammatical forms are specific to the region. Beginning in the 1940s several regional atlas projects were implemented by dialect geographers and linguists in an attempt to form a baseline of language patterns in the United States. In part because of these efforts, most linguists now recognize North Central, Midland, Southern, and Western dialect areas converging in the Great Plains.

The North Central area extends from the western boundary of North Dakota southward to Sioux Falls, South Dakota. Examples of terms common to the Northern Plains include "soddy" for a house constructed of tough prairie sod and "sodbuster" for the one who breaks the sod. The need for trees in some Northern Plains areas during their settlement years brought legislation to encourage tree planting on "tree claims," a term that persists in the eastern Dakotas to describe woodlots. Another example can be seen in the use of "borrow pit" or "bar pit" as a road-building term that describes a place where earthen material has been removed.

The Midland area, extending westward from Philadelphia and represented in the Great Plains in a zone from Lincoln, Nebraska, southwest toward Amarillo, Texas, is widely considered to be the most important dialect region. This area forms a transition zone between the north dialect stream and the region dominated by southern speech forms. Because it is a transition zone in terms of language features, the Midland region is difficult to distinguish and may be the most unmarked in terms of a unique dialect.

Extending into southern Oklahoma and most of Texas south of Amarillo, the Southern dialect region is the speech region most easily identified by the American public. The vocabulary of this area includes the word "blinky" as an adjective to describe milk that has begun to sour. Another colorful term, "gully washer," refers to an exceptional amount of rainfall, and in Texas a compliment might be paid to someone who was said to be as "handy as hip pockets on a hog." The Spanish language has also had a profound impact on folk speech in this part of the Plains, as represented in terms such as "arroyo," meaning a dry gulch or deep gully cut by an intermittent stream.

The Northern, Midland, and Southern dialect areas merge with Western dialect forms in the western reaches of the Plains. Western dialect terms that mingle within the Great Plains include "corral," "bull snake," and "jerky." Slang terms are also an important part of folk speech, as represented by "Wyoming wind gauge," used for a logging chain on a fence post. Native American and First Nation languages have also influenced Plains folk speech: in the Prairie Provinces, for example, the verb "ponask" has been borrowed from the Cree language to describe the practice of splitting a piece of meat, putting it on a stick, and roasting it over an open fire.

Distinctive folk speech of the Great Plains can also be found within enclaves or ethnic islands. These include places settled by European immigrants who have retained distinctive, yet not necessarily foreign-sounding, elements in their speech. Language retention is important, for example, to many ethnic Ukrainians whose ancestors migrated to Manitoba beginning in the 1890s. In some cases the Ukrainian language has blended with English, as represented in words such as (drugstore).

In many cases, unique forms of folk speech in a particular area may have grown out of isolation from mainstream society. During the early years of settlement, particular forms of grammar, word usage, and pronunciations were also born out of necessity or emerged from the imagination of settlers. For example, a tree common to the Plains, the "bois d'arc" (Maclura pomifera), was named by the French for the Indian use of bois for the wood used to construct the bow (arc). Americanization replaced bois d'arc with "bowdark" and added the term "horse apples" for the bowdark's fruit.