According to the World Atlas
The County Seats That Aren’t The Biggest Town Upper Marlboro, Maryland, has 652 residents. The county it governs has nearly a million. Legislatures fixed county seats early in American history, and courthouses have almost never moved since. Railroads, highways, and subdivisions proved far less loyal. Upper Marlboro is one of nine towns that never gave up their county’s courthouse, and a larger nearby place absorbed their population instead. Every figure here is based on a 2020 census count, noting that the census counts communities that no state has ever incorporated alongside the ones it has. Where the courthouse came before the country The Oldest County Seats In America Upper Marlboro, Maryland Upper Marlboro, Prince Georges County, Maryland.
Upper Marlboro is perhaps the most surprising entry on this list. Its 652 residents administer nothing beyond their own town limits, yet Prince George’s County reported 967,201 people, second only to Montgomery among Maryland counties. Bowie leads the county’s municipalities at 58,329, and no unincorporated community here approaches that figure either. Maryland granted the town its charter in 1870, more than 170 years after the county was erected from Calvert and Charles in 1695. Prince George of Denmark, husband of Queen Anne, supplied the name.
A five-member Board of Commissioners runs the town, and the commissioners choose their mayor from among themselves. Roughly 1,500 times as many people fall under the government that works out of the County Administration Building on Gov. Oden Bowie Drive. Upper Marlboro also keeps the circuit court and the official county address. Bowie has the residents, a municipal government of its own, and no claim on any of that.
https://www.worldatlas.com/county/the-county-seats-that-aren-t-the-biggest-town.html
