A county seat is a town which is the capital of a county. It is often, but not always, an incorporated municipality. County-wide politics and government are conducted here. The county courthouse and county administration are usually located in the county seat.

In the United Kingdom and Ireland, the term county town is usually used for the same purpose.

Special U.S. circumstances

The power of the county government varies widely from state to state as does the relationship between counties and incorporated municipal governments.

• In Virginia, many county seats are politically not a part of the counties they serve; under Virginia law, all municipalities incorporated as cities are independent cities and are not part of any county. Some of the cities in the Hampton Roads area (Virginia Beach, Chesapeake, Newport News, Hampton, and Suffolk) were formed from an entire county. These cities are no longer county seats, since the counties ceased to exist once the cities were completely formed, but are functionally equivalent to counties.
• New York City encompasses five counties, and is the county seat of four of them: New York County (Manhattan), Kings County (Brooklyn), Bronx County (The Bronx), and Richmond County (Staten Island). The county seat of Queens County (Queens) is Jamaica, a community located within Queens.
• In some New England states, such as Connecticut, parts of Massachusetts, and Rhode Island, counties are only geographic designations and do not have any governmental powers. All government is either done at the state level or at the municipal (town or city) level.
• In Louisiana, the parish is the name used for counties. As such, the parish seat would be the equivalent of the county seat. The city of New Orleans is coterminous with, and identical to, Orleans Parish.
• The state of California has one consolidated city-county, San Francisco. The city's board of supervisors govern both aspects, and there is both a city police department and a county sheriff, the latter mostly responsible for operating the county jail (which is located in adjacent San Mateo County).

• In Pennsylvania the city of Philadelphia also has the status of a county. In Maryland the city of Baltimore is distinct from the county of Baltimore, which has its county seat in Towson.
• In Missouri, St. Louis City is separate from St. Louis County and is referred to as a "city not within a county."
• In Kansas, Wyandotte County and the city of Kansas City, Kansas operate as a unified government.

See also: borough seat (Alaska), parish seat (Louisiana), and shire town (Vermont).