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County police are the police of a county in the United States, Sweden and England and Wales in the UK, Scotland now has a single and only region wide police force Police Scotland, as well as Northern Ireland whose regional and only police are the Police Service of Northern Ireland.
Police forces in Scotland and Wales also used to be organised on a county basis, but then were amalgamated into a number of larger regional forces: eight in Scotland and four in Wales. In 2013, Scotland ditched it's eight regional forces and created one national police force known as Police Scotland.
Northern Ireland is historically policed on a national basis, first by the Royal Irish Constabulary, then the Royal Ulster Constabulary, which was reformed in 2001 as the Police Service of Northern Ireland. Northern Ireland has never been policed on a county basis.
Other Special Police Services that have a presence at a country level are in operation throughout the UK, such as the British Transport Police who mainly police the transport services such as public trains, train stations, buses, bus stations & trams in the UK. The Nuclear Constabulary which is responsible for providing law enforcement and security at or within 5 km of any relevant nuclear site and for nuclear materials in transit within the United Kingdom. The Ministry of Defence Police of which their primary responsibilities are to provide armed security and to counter terrorism, as well as uniformed policing and investigative services to Ministry of Defence property, personnel, and installations throughout the United Kingdom. Others also include the Royal Military Police, Royal Navy Police, Royal Air Force Police and more.
Depending on the jurisdiction, in the United States, county police tend to exist only in metropolitan counties and have countywide jurisdiction. In some areas, there is a sheriff's department which only handles issues such as service of papers such as a constable in other areas, along with security for the local courthouse. In other areas, there are no county police and the local sheriff is the exclusive law enforcement agency and acts as both sheriff and county police, which is much more common than there being a separate county police force. County police tend to fall into three broad categories:
- Full-service police departments, which provide the full spectrum of police services to the entire county, irrespective of local communities, and may provide contractual security police services to special districts within the county.
- Hawaii has only county police; there are no local police.
- Limited service police departments, which provide services to unincorporated areas of the county (and may provide services to some incorporated areas by contract), and usually provide contractual security police services to special districts within the county.
- Restricted service police departments, which provide security police duties to county owned and operated facilities and parks. Some may also perform some road patrol duties on county built and maintained roads, and provide support to municipal police departments in the county.
Note: County detectives, who are maintained in the northeastern states by county attorneys' offices, fall within this category. In the state of Louisiana, a county is known as a parish. In the state of Alaska, a county is known as a borough. The only of which to have their own police department is North Slope Borough.
There are 3,141 counties in the United States and some county police departments are:
A to M
- Albemarle County Police Department, Albemarle County, Virginia - full service
- Allegany County Bureau of Police, Allegany County, Maryland - full service, a division of the Allegany County Sheriff's Office.
- Allegheny County Police Department, Allegheny County, Pennsylvania - County-wide Authority - Detective Div.- Uniform patrol county facilities and property.
- Anne Arundel County Police Department, Anne Arundel County, Maryland - full service
- Arlington County Police Department, Arlington County, Virginia - full service
- Athens-Clarke County Police Department, Clarke County, Georgia - full service
- Augusta-Richmond County Police Department, Richmond County, Georgia - full service
- Andrew County Police Department, Andrew County, Missouri
- Baltimore County Police, Baltimore County, Maryland - full service
- Bergen County Police Department,  Bergen County, New Jersey - limited service
- Boyd County Police Department, Boyd County, Kentucky - limited service
- Broome County Sheriff's Department, Broome County, New York - full service
- Broomfield Police Department, City and County of Broomfield, Colorado - full service
- Broward County Department of Law Enforcement, Broward County, Florida
- Camden County Police Department, Camden County, New Jersey - full service
- Charlotte-Mecklenburg Police Department, Mecklenburg County, North Carolina - full service
- Chesterfield County Police Department, Chesterfield County, Virginia - full service
- Clark County Park Police, Clark County, Nevada - restricted service
- Clayton County Police Department, Clayton County, Georgia - limited service
- Cobb County Police Department, Cobb County, Georgia - full service
- Cook County Sheriff's Office, Cook County, Illinois - limited service
- DeKalb County Sheriff's Office, DeKalb County, Alabama - full service
- DeKalb County Police Department, DeKalb County, Georgia - limited service (By statute, DKPD has authority throughout the entire county, but yields this authority to incorporated municipalities that provide their own police services.)
- Delaware County Courthouse and Park Police Department, Delaware County, Pennsylvania - restricted service
- Denver Police Department, City and County of Denver, Colorado - full service
- Dougherty County Police Department, Dougherty County, Georgia - limited service
- Fairfax County Police Department, Fairfax County, Virginia - full service
- Floyd County Sheriff's Office, Floyd County, Georgia - limited service
- Fulton County Sheriff's Office, Fulton County, Georgia - limited service
- Gaston County Police Department, Gaston County, North Carolina - limited service
- Glynn County Police Department, Glynn County, Georgia
- Gratiot County Police Department, Gratiot County, Michigan
- Gwinnett County Police Department, Gwinnett County, Georgia - full service (serves unincorporated Gwinnett County, and the cities of Berkeley Lake, Buford, Dacula, Grayson, Rest Haven, and Sugar Hill)
- Hawai‘i County Police Department, Hawaii County, Hawaii - full service
- Henrico County Police Department, Henrico County, Virginia - full service
- Henry County Police Department, Henry County, Georgia - limited service
- Honolulu Police Department, City and County of Honolulu, Hawaii - full service
- Horry County Police Department, Horry County, South Carolina - limited service (full-time service of all unincorporated areas of Horry County, South Carolina and part-time service of certain municipalities within the county by contract)
- Houston County Sheriff's Department, Houston County, Georgia - limited service
- Howard County Police Department, Howard County, Maryland - full service
- James City County Police Department, James City County, Virginia - full service
- Johnson County Sheriffs Department, Johnson County, Kentucky -Full Service
- Kauai County Police Department, Kauai County, Hawaii - full service
- Kenton County Police Department, Kenton County, Kentucky - limited service
- Las Vegas Metropolitan Police Department, Clark County, Nevada - limited service
- Lexington Division of Police, Fayette County, Kentucky - full service
- Louisville Metro Police Department, Louisville and Jefferson County, Kentucky
- Maryland-National Capital Park Police Department, Montgomery County, Maryland and Prince George's County, Maryland - restricted service
- Maui County Police Department, Maui County, Hawaii - full service
- Metropolitan Nashville Police Department, Davidson County, Tennessee - full service
- Miami-Dade Police Department, Miami-Dade County, Florida - limited service
- Montgomery County Police Department, Montgomery County, Maryland - full service
- Morris County Park Police Department, Morris County, New Jersey - restricted service
N to Z
- Nassau County Police Department, Nassau County, New York - full service
- New Castle County Police Department, New Castle County, Delaware - full service
- New Orleans Police Department, Orleans Parish, Louisiana - full service
- New York City Police Department, covers five New York counties, Bronx County, Kings County, New York County, Queens County, and Richmond County - full service
- Oldham County Police Department, Oldham County, Kentucky - limited service
- Onondaga County Sheriff's Office, Onondaga County, New York - full service
- Philadelphia Police Department, Philadelphia County, Pennsylvania - full service
- Pima County Park Police Department, Pima County, Arizona - restricted service
- Prince George County Police Department, Prince George County, Virginia - Full Service
- Prince George's County Police Department, Prince George's County, Maryland - Full service
- Prince William County Police Department, Prince William County, Virginia - Full service
- Polk County Police Department, Polk County, Georgia - limited service
- Riley County Police Department, Riley County, Kansas - full service
- Roanoke County Police Department, Roanoke County, Virginia - full service
- St. Joseph County Police Department, St. Joseph County, Indiana - limited service
- St. Louis County Police Department, St. Louis County, Missouri - full-service
- San Francisco Police Department, City and County of San Francisco, California - full service
- Savannah-Chatham Metropolitan Police Department, Chatham County, Georgia - limited service (serves the city of Savannah and unincorporated Chatham County)
- Spotsylvania County Sheriff's Office, Spotsylvania Virginia
- Suffolk County Park Police Department, Suffolk County, New York - restricted service
- Suffolk County Police Department, Suffolk County, New York - limited service
- Union County Police Department, Union County, New Jersey - restricted service
- Westchester County Department of Public Safety , Westchester County, New York - restricted service
- Westmoreland County Park Police Department, Westmoreland County, Pennsylvania - restricted service