What is a county?
The county is usually the oldest and most durable local boundary in the United States.
What counties do
Counties run courts, jails, property records, elections, public health departments and, outside city limits, roads and policing. In many states they also assess property taxes and issue marriage licences and permits. City governments handle municipal services inside their boundaries; the county covers everything else.
Not every state uses the word
Louisiana calls its equivalents parishes; Alaska has boroughs plus a vast "unorganized borough" with no county government at all. Connecticut, Rhode Island and parts of Massachusetts have counties only as geographic labels, with no county government left. Puerto Rico uses municipios, which function as both county and city.
Counties do not move, cities do
County boundaries are extremely stable — most date from the nineteenth century. City boundaries expand constantly through annexation. That is why a house can be inside a city that grew into a neighbouring county, and why a ZIP code (a mail route) may cross a county line while the city does not.
Finding which county a place is in
Search the place here: every place page lists its primary county, and any additional counties it extends into. County pages then list the cities, towns and CDPs inside them.
Frequently asked questions
What is the difference between a county and a city?
A city is an incorporated municipality with its own government; a county is the larger local division that provides courts, records and services across cities and unincorporated land.
Does every US state have counties?
Almost all do, but Louisiana has parishes, Alaska has boroughs, and some New England counties have no government.
Can a city be in two counties?
Yes. Annexation and geography mean many cities span a county line; the place page here lists every county it touches.