Sociolinguistics 2, Exercise 3: borders and continua

Political boundaries often cut across continua. Speakers on either side of the
border may use nearly identical varieties, but each side depends on a
different standard (its own codified dictionaries, grammars, schooling and
broadcasting). Since a standard variety serves as the authority for local
dialects, the two sides are treated as speaking different languages, even
though the speech itself changes little at the border.

Haugen's four steps by which a dialect can be promoted to an independent
language: selection, codification, elaboration, acceptance.

Source: Wikipedia, Dialect continuum and Dialect.