The short version
Maricopa County is the state of Arizona’s local arm in the Valley. It runs the elections, values and bills property, keeps the jails, prosecutes felonies, tracks disease, and governs every acre no city has claimed. Sitting on top of all that is a five-member Board of Supervisors, part legislature and part executive, which adopts the budget and sets the county’s property tax rate, then hands the day-to-day work to a professional county manager it appoints.
The scale is hard to picture. The county covers 9,224 square miles, larger than four U.S. states, and holds about 4.7 million people, more than half of Arizona and the fourth largest population of any county in the country. Scottsdale is one of about two dozen cities and towns inside it.
Who sits on the board
Each supervisor is elected by one of five districts in partisan races, for four-year terms, and all five seats are on the ballot together in presidential years. As of 2026 Republicans hold four seats and Democrats one, and Kate Brophy McGee chairs the board, a post the members fill each year. Under the map drawn after the 2020 census, Scottsdale is split between District 1 and District 2, represented as of 2026 by Mark Stewart and Thomas Galvin.
Why a Scottsdale resident should care
The city handles police, water and zoning, so the county can feel distant. But the ballot you mark in a city election is printed, counted and certified by the county (see elections in Maricopa County). Your property tax bill comes from the county Treasurer and the value on it from the county Assessor (see property taxes). A person arrested by Scottsdale police on a felony is booked into a county jail and prosecuted by the County Attorney. And the board’s budget pays for all of it, which gives five supervisors real leverage over officials they don’t control, the subject of the elected officers guide.
An arm of the state
A city like Scottsdale can adopt a home-rule charter and run its local affairs its own way. A county can’t, in practice. Arizona’s constitution and courts treat counties as political subdivisions of the state, created to carry out state functions locally, with only the powers the legislature grants in statute (mostly Title 11 of the Arizona Revised Statutes). A 1992 amendment lets counties of more than 500,000 people write a charter, but Maricopa never has, so when the board wants a new power it has to ask the legislature. The preemption and home rule guide covers how that plays out at the city level too.
What the money buys
The board adopted a budget of about $4.1 billion for fiscal 2027 on June 22, 2026, and cut the county’s property tax rate for the sixth year in a row. Public safety (the sheriff, the jails, the prosecutor, the public defenders and the courts) takes the largest share, and state mandates, such as the county’s required contributions to health care and juvenile corrections, take a big bite of the general fund before the board makes a single choice. The county services guide covers the departments the manager runs, from public health and air quality to animal care.
The county at Scottsdale’s edges
Beyond the city limits the board is the local government. In unincorporated communities it adopts the zoning, the sheriff patrols and county roads crews maintain the streets. That is why the Rio Verde Foothills water cutoff was, underneath, a county story: a community that grew up under county rules, with no city utility of its own. The county’s McDowell Mountain Regional Park, just past the city’s northeast edge, is another reminder that the county’s map doesn’t stop at Scottsdale’s. See the unincorporated county guide.
From Yavapai County to the fourth largest in the country
Maricopa County was proclaimed on February 14, 1871, carved out of Yavapai County by the territorial government, and in May of that year voters ratified Phoenix, then a young farm town on the Salt River canals, as its seat. By a coincidence of the calendar, Arizona became a state on the same date 41 years later, February 14, 1912. The county’s lines were fixed in 1881 and haven’t moved since; what changed was everything inside them.
For its first eight decades the county was the only local government most of the Scottsdale area knew. When residents of the little townsite petitioned to incorporate in 1951, it was the supervisors who certified the petition, and appointed the first council on June 25, 1951. Every annexation Scottsdale made afterward, as it stretched north toward the McDowells, took land out of the county’s direct care and put it under the city’s.
Why five supervisors can’t run the whole county
The board’s power looks sweeping on paper: the budget, the tax rate, zoning outside cities, the Election Day half of every election. But Arizona’s constitution also creates a slate of independently elected county officers, from the sheriff and county attorney to the assessor, recorder and treasurer. The board funds them but cannot direct how they do their jobs. That arrangement produces a recurring pattern in Maricopa politics: the board uses the budget as its lever, and the officers go to court.
The sharpest recent example is elections. In late 2024 the board and then-Recorder Stephen Richer signed a shared-services agreement that moved election staff and technology under the board. His successor, Justin Heap, sued in 2025, arguing the deal stripped duties the legislature had given his office. A Superior Court judge ruled for him in April 2026, and on July 7 the Arizona Supreme Court unanimously held that the board cannot use its budget power to take over the recorder’s statutory duties. The two sides settled in July, splitting early voting (the recorder) from Election Day voting and tabulation (the board). The elections guide explains what that means for a Scottsdale voter.
Partisan by design
Unlike Scottsdale’s nonpartisan, citywide council, supervisors run by district under party labels, so a supervisor’s first test is a party primary. That structure has produced a board whose members sometimes break with their own party’s activists, most visibly after 2020, when the Republican-majority board defended the county’s election results against challenges from within the GOP. District lines matter too: because Scottsdale is split between two districts, the city has two voices on the board rather than one, and neither district is Scottsdale alone.