In United States local government, a consolidated city-county is formed when one or more cities and their surrounding county (parish in Louisiana, borough in Alaska) merge into one unified jurisdiction. As such it has the governmental powers of both a municipal corporation and an administrative division of a state.
A consolidated city-county is different from an independent city, although the latter may result from consolidation of a city and a county and may also have the same powers as a consolidated city-county. An independent city is a city not deemed by its state to be located within the boundary of any county and recognized by its state as a legal territorial entity separate from surrounding or adjoining counties. A consolidated city-county differs from an independent city in that the city and county both nominally exist, although they have a consolidated government, whereas in an independent city, the county does not even nominally exist.
Not considering Hawaii, which has no independent municipalities, the Midwest and Upper South have the highest concentration of large consolidated city-county governments in the United States, including Indianapolis, Indiana; Nashville, Tennessee; Louisville, Kentucky; Kansas City, Kansas; and Lexington, Kentucky. Currently, the largest consolidated city-county in the United States by population is Philadelphia, Pennsylvania, while the largest by land area is Sitka, Alaska.
Consolidated city-counties are typically formed to address particular government challenges. Among the benefits of having a unified jurisdiction include potential cost savings, more efficiency, increased legal powers and revenue sources, and a more streamlined planning system.
Most consolidated city-counties have a single chief executive that acts as both the city mayor and as the head of the county government, and a multi-district elected body that serves as both the city council and as the county legislative body.
In many states, consolidated city-counties must be approved by voters. According to information compiled by former Albuquerque mayor David Rusk, 105 referenda were held in the United States between 1902 and 2010 to consider proposals to consolidate cities and counties. Only 27 of these proposals were approved by voters.
Wyandotte County, Kansas, uses the term "unified government" to refer to its consolidation with Kansas City, Kansas, and most of the towns within the county boundaries in which some cities and towns remain separate jurisdictions within the county. Individual sections of a metropolitan or regional municipality may retain some autonomous jurisdiction apart from the citywide government.
Often, in place of another level of government, local governments form councils of governments – essentially governmental organizations which are not empowered with any law-making or law enforcement powers. This is the case in the Atlanta metropolitan area, where the Atlanta Regional Commission (ARC) studies and makes recommendations on the impact of all major construction and development projects on the region, but generally cannot stop them. The Georgia Regional Transportation Authority (GRTA) is a true government agency of the state of Georgia, and does control some state transportation funding to the cities and counties, but otherwise has very little authority beyond this small power of the purse.
The case of New York City is unique, in that the city consists of five boroughs, each of which is co-extensive with a county. Each borough, being coterminous with a county, has its own district attorney; however, county-level government is essentially non-existent as all executive and legislative power is exercised by the city government throughout the five boroughs. The city, as currently constituted, was created in 1898 when the city of New York (then comprising what would become the boroughs of Manhattan and The Bronx) annexed Kings County, Queens County, and Richmond County as the boroughs of Brooklyn, Queens, and Staten Island, respectively.
Similar arrangements also exist in other countries. England has six "metropolitan counties" created in 1974: Greater Manchester, Merseyside, South Yorkshire, Tyne and Wear, West Midlands, and West Yorkshire. From 1986, these metropolitan counties do not have county councils but rather joint boards for certain functions. Modern unitary authorities are similar, and are known as county boroughs in Wales. In Scotland, Aberdeen, Dundee, Edinburgh and Glasgow are functionally "independent cities", though the term is not used. London is unique however, being a ceremonial county (officially known as Greater London) containing the 32 London boroughs. Enclaved within Greater London, the ancient City of London forms a distinct county, which today forms only a tiny part of what most consider to be London as a capital city, which takes up 607 square miles.
In the Canadian province of Ontario, there exist several single-tier municipalities which serve the same sort of functions as American consolidated city-counties. One example of this is the City of Toronto, which was created in 1998 from the amalgamation of the central government and the six constituent municipalities of the Municipality of Metropolitan Toronto (a type of regional municipality) which was originally created in 1954.
In Germany, Berlin and Hamburg are both cities and states (the state of Bremen consists of the cities of Bremen and Bremerhaven). Nearly every larger city in Germany is a consolidated city-county, like Frankfurt, Stuttgart, Munich or Dresden; Austria, where the capital of Vienna is both a city and state; France, where the capital city of Paris has been coterminous with the département of Paris since 1968; and South Korea, where Seoul is a special city, while six other cities (Busan, Daegu, Daejeon, Gwangju, Incheon, and Ulsan) are metropolitan cities. Additionally, the Australian Capital Territory government in Australia performs all municipal functions of the city of Canberra, and thus functions as an integrated city-territory. Similarly, the City of Tokyo merged with the prefecture to form Tokyo metropolis in 1943.