company town

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A town whose residents are dependent on the economic support of a single firm for maintenance of retail stores, schools, hospitals, and housing.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A town, city, or other municipality in which a single large business has a controlling influence over the economy and, sometimes, over the societal structure and local government.