A merger or amalgamation in a political or administrative sense is the combination of two or more political or administrative entities such as municipalities

Municipality

A municipality is essentially an urban administrative division having corporate status and usually powers of self-government. It can also be used to mean the governing body of a municipality. A municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district...

 (in other words cities

City

A city is a relatively large and permanent settlement. Although there is no agreement on how a city is distinguished from a town within general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.For example, in the U.S...

, town

Town

A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...

s, etc.), counties

County

A county is a jurisdiction of local government in certain modern nations. Historically in mainland Europe, the original French term, comté, and its equivalents in other languages denoted a jurisdiction under the sovereignty of a count A county is a jurisdiction of local government in certain...

, district

District

Districts are a type of administrative division, in some countries managed by a local government. They vary greatly in size, spanning entire regions or counties, several municipalities, or subdivisions of municipalities.-Austria:...

s, etc. into a single entity. This term is used when the process occurs within a sovereign entity. In United States politics, such an entity may be called a consolidated city–county. Unbalanced growth or outward expansion of one neighbor may necessitate an administrative decision to merge (see urban sprawl

Urban sprawl

Urban sprawl, also known as suburban sprawl, is a multifaceted concept, which includes the spreading outwards of a city and its suburbs to its outskirts to low-density and auto-dependent development on rural land, high segregation of uses Urban sprawl, also known as suburban sprawl, is a...

).