Arizona is divided into 30 legislative districts, and each one elects a single member to the Arizona State Senate along with two members to the state House. Those 30 Arizona State Senate districts are drawn once a decade by an Independent Redistricting Commission rather than by the legislature itself, and the current boundaries, adopted in January 2022, will govern elections through the end of the decade.
How the 30 Districts Are Structured
The Arizona Constitution divides the state into 30 legislative districts of roughly equal population.1Arizona Legislature. Arizona Constitution, Article 4, Part 2, Section 1 Each district sends one senator to the 30-member Senate and two members to the 60-member House of Representatives.2Arizona Legislature. Arizona State Legislature Homepage Every Arizonan therefore has three state lawmakers tied to the same district number: one senator and two representatives.
Federal equal-protection rules require state legislative districts to be substantially equal in population. Courts have generally allowed a total deviation of less than 10 percent between the most and least populous districts. In the 2016 case Harris v. Arizona Independent Redistricting Commission, the U.S. Supreme Court upheld an Arizona legislative map with an 8.8 percent deviation, finding it constitutional in part because the deviation helped the state comply with the Voting Rights Act.3Arizona Legislature. Arizona Reapportionment and Redistricting 2022
Who Draws the District Lines
Arizona’s redistricting process is unusual. In November 2000, voters approved Proposition 106, a citizen initiative that took the power to draw district lines away from the legislature and gave it to an Independent Redistricting Commission. The stated goal was to curb gerrymandering and encourage broader voter and candidate participation.4Arizona Secretary of State. Proposition 106
The commission has five members. The Commission on Appellate Court Appointments assembles a pool of 25 nominees: 10 from each of the two largest parties and 5 who are unaffiliated. Four commissioners are then appointed by legislative leaders, one each by the House Speaker, the House Minority Leader, the Senate President, and the Senate Minority Leader. Those four choose a fifth member to serve as chair, who cannot belong to any party already represented on the commission.4Arizona Secretary of State. Proposition 106 Commissioners must have been registered voters for at least three years and cannot have recently held public office, served as a party officer, or worked as a registered lobbyist.1Arizona Legislature. Arizona Constitution, Article 4, Part 2, Section 1
The mapping process starts with a grid of equal-population districts and then adjusts for several constitutional goals: compliance with the U.S. Constitution and the Voting Rights Act, geographic compactness and contiguity, respect for communities of interest, use of visible geographic features, and, where it would not significantly harm the other goals, competitive districts. Party registration data and voting history are excluded from the initial phase, and the residences of incumbents and candidates are not considered. Draft maps go through a 30-day public comment period before the commission finalizes them.4Arizona Secretary of State. Proposition 106
The Current Map, 2022 Through 2030
A new IRC was appointed in January 2021 to redraw the state’s districts using 2020 Census results. The commission adopted the current legislative map, officially designated Version 17.0, on January 21, 2022, by a 3-2 vote.5All About Redistricting. Arizona Redistricting The final version built on a draft approved in December 2021 and included technical cleanups requested by county election officials, such as the elimination of small slivers and unnecessary district splits.6Arizona IRC. Official Maps It replaced the map drawn after the 2010 Census, which had been in effect since April 2012. The final 2020-cycle legislative plan does not appear to have been challenged in court.
Of the 30 districts, 22 fall at least partly within Maricopa County, which encompasses the Phoenix metropolitan area: Districts 2, 3, 4, 5, 8, 9, 10, 11, 12, 13, 14, 15, 16, 22, 23, 24, 25, 26, 27, 28, 29, and 30.7Maricopa County. Election Maps The remaining districts cover southern Arizona including the Tucson area in Pima County, the state’s rural northern and western regions, and tribal lands.
How to Find Your District and Senator
Several free tools let Arizona residents identify their legislative district and the lawmakers who represent them. The IRC maintains an online Legislative District Lookup where you enter a home address and immediately see your district number.8Arizona Legislature. How Can I Determine My District and Legislator The Citizens Clean Elections Commission offers a similar District Locator that returns the district along with the names of the corresponding senator and two representatives; addresses entered into that tool are not stored or shared.9Arizona Clean Elections Commission. District Locator Once you know your district number, the member roster on the Arizona Legislature website lists each district’s senator and representatives with contact information.10Arizona Legislature. Member Roster
Because redistricting follows each decennial census, your district number can change even if you have not moved. If you last checked before 2022, check again.
Senate Terms, Elections, and Vacancies
Arizona state senators serve two-year terms and are elected in both presidential and midterm years.11Arizona Secretary of State. Elected Office Terms Under the Arizona Constitution, senators are limited to four consecutive terms. After serving the maximum, a senator must sit out at least one full term before running for the same office again. The term-limit provision applies to terms beginning on or after January 1, 1993.12Arizona State Legislature. Arizona Constitution, Article 4, Part 2, Section 21
When a Senate seat becomes vacant mid-term, the precinct committeemen of the departing senator’s party in that district nominate three candidates. Those names go to the county board of supervisors, which selects one person from the list to fill the seat. State law does not impose a specific deadline for the appointment, though in Maricopa County the process typically includes background checks and interviews before the board votes.13Maricopa County. Legislative Vacancy Appointment Process
Current Balance and Competitive Districts
Following the 2024 elections, Republicans hold a 17-13 majority in the Senate.14Arizona Capitol Times. Legislature 2024: Republicans End Year With Expanded Majority Senate President Warren Petersen, a Gilbert attorney and real estate veteran who has served in the legislature since 2012, represents District 14.15Arizona Water Bank Authority. Warren Petersen Minority Leader Priya Sundareshan, a natural resources law professor at the University of Arizona, represents District 18.16Arizona Legislature. Senator Priya Sundareshan
Only a handful of districts actually swing. The 2024 general election expanded the Republican Senate majority by one seat as three swing districts, LD 4, LD 13, and LD 16, flipped from Democratic to Republican control. In LD 16, Republican Carine Werner defeated incumbent Senator Christine Marsh of Phoenix. The only seat Republicans lost was LD 17, where Democrat Kevin Volk unseated Republican incumbent Cory McGarr in Tucson.14Arizona Capitol Times. Legislature 2024: Republicans End Year With Expanded Majority In a chamber of 30, a few competitive suburban districts around Phoenix and Tucson decide which party runs the Senate.