There are three main sources of variation in spoken language:1. Language internal pressures, arising in part from the
mechanics of production and perception.
2. External influences on language, such as geographic mobility
and social behavior subject to normative and other formative
social pressures.
3. Variation arising from language as a creative vehicle of free
expression.These forces can and do function in tandem, and any good study of
language change in progress will consider at least the first two together.
Variation over space is the dimension that most people seem to be aware
of, but in a limited way. There are language communities of well-
established, self-contained or isolated religious groups that mark their
English for insider/outsider status (the Amish and Mennonites in
Pennsylvania; Mormons in Utah and Arizona; Jews in Williamsburg and
the greater New York City area, Hassidic Jews in Brookline, outside of
Boston). There are historical language communities which remain
bilingual despite outside pressures (German in parts of Michigan and
Texas, French (independent of the Creole communities in Louisiana)
(Figure 1.1), bilingual pockets in New England and Louisiana.