Counties of Arizona: overview, list, history and governance

Structure and responsibilities

Each county has an elected governing body (often called a board of supervisors or county commission) and a county seat that hosts central offices and courts. County responsibilities vary by statute and local practice but typically include public health, elections administration, land records, and some social services. County sheriffs and county attorneys perform law enforcement and prosecutorial functions respectively. For additional administrative details see county government.

List of counties

The state's counties range from urban population centers to vast rural expanses. Below is the complete list of Arizona's 15 counties with their county seats in parentheses:

• Apache (St. Johns)
• Cochise (Bisbee)
• Coconino (Flagstaff)
• Gila (Globe)
• Graham (Safford)
• Greenlee (Clifton)
• La Paz (Parker)
• Maricopa (Phoenix)
• Mohave (Kingman)
• Navajo (Holbrook)
• Pima (Tucson)
• Pinal (Florence)
• Santa Cruz (Nogales)
• Yavapai (Prescott)
• Yuma (Yuma)

History and name origins

County boundaries in Arizona evolved during the territorial era and after statehood in 1912. Several counties trace their origins to formations in the 1860s when the region was organized as the Arizona Territory. A short-lived Pah-Ute County existed in the 1860s before much of its area was transferred to neighboring Nevada. Many county names reflect the cultural history of the region: numerous counties bear names derived from Indigenous groups and languages, while others preserve Spanish-era names or honor early settlers and local geographic features. Learn more about the state's geography and history at the Arizona state overview and resources on Indigenous peoples of the region.

Notable distinctions and contemporary importance

Counties in Arizona differ widely by population and land area. Maricopa County, which contains Phoenix, is the state's most populous county and a major economic and political center. Coconino County is the largest by land area and includes significant public lands and national park and forest areas. La Paz is the most recently organized county, created from parts of an older county during the 20th century. The diversity of county types—urban, suburban, agricultural and remote rural or reservation lands—shapes policy priorities and service delivery across the state.

Practical uses and research

Knowing county boundaries is important for property transactions, voting and elections, public health reporting, emergency services, and demographic or economic research. State and local agencies publish maps, statistics and county-level data that researchers, planners and residents use to compare trends, allocate funding, and plan infrastructure. For citizens, county offices are primary points of contact for records, permits and local administration; for broader context on the state's subdivisions see general information about the U.S. state system of counties.