In United States local government, a consolidated city-county (see below for alternative terms) 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 is a type of unitary authority that has the governmental powers of both a municipal corporation and a county.

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 considered a primary administrative division of its state. 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. Furthermore, a consolidated city-county may still contain independent municipalities maintaining some governmental powers that did not merge with the rest of the county.

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. The largest consolidated city-county in the United States by population is Philadelphia, Pennsylvania, while the largest by land area is Sitka, Alaska.

The term consolidated city-county refers to a consolidated jurisdiction in a state that is otherwise divided into counties. In Louisiana, which is divided into parishes, the equivalent jurisdiction is known as either a city-parish or a consolidated government, depending on the locality. In Alaska, it is known as a unified municipality, unified home rule borough, or city and borough. The United States Census Bureau generically refers to any such jurisdiction as a consolidated city, regardless of the jurisdiction into with the city has consolidated. Although California is divided into counties, a consolidated city-county is officially termed a city and county.

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 who 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 referendums 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 remain separate jurisdictions within the county. Individual sections of a metropolitan or regional municipality may retain some autonomous jurisdiction apart from the citywide government.