Ballotpedia completed an inventory of all Arizona ballot measures since 1911, the year before statehood, and when voters adopted the initiative and referendum process. Between 1911 and 2024, Arizonans voted on 476 ballot measures. Two hundred and fifty-one (251) measures were approved, and 225 measures were defeated.

In Arizona, measures can be placed on the ballot through the state legislature, as well as through citizen initiatives. The Arizona State Legislature has voted to refer 257 ballot measures to the state ballot between 1911 and 2024, while citizen initiatives made up 219 of the measures on the ballot. Legislatively referred measures were approved 60% of the time, compared to 45% for ballot initiatives.

There are six different types of ballot measures in Arizona. Legislatively referred constitutional amendments have appeared on the ballot the most times (221). Constitutional convention questions had the highest success rate, with both measures approved by voters. Initiated state statutes had the lowest success rate, with 43.75% of the 112 measures approved by voters.

Arizona ballot measures have addressed 80 unique topics with some addressing multiple topics in one measure. The top three topics were administration of government (90 measures), taxes (73 measures), and business regulation (40 measures). Other notable topics in Arizona included direct democracy, immigration, the size of the state legislature, and the death penalty.

Of the 476 ballot measures on the statewide ballot in Arizona, 12 were decided by less than a percentage point of the vote. The measure with the closest margin was Proposition 112, decided by voters in 2010, which would have changed the initiative filing deadline from four months to six months before the general election in which the measure would have been voted on. The measure was defeated with 49.99% of voters approving the measure and 50.01% of voters defeating the measure. It was the only statewide measure in Arizona’s history with a vote margin of 0.01%.

Meanwhile, the measure with the widest margin was the Constitution Ratification Question in 1911, which ratified the proposed Arizona Constitution. This measure was decided with 88.79% voting for it, and 11.21% voting against it, a margin of 77.57%.

The decade with the most ballot measures was the 2000s, which featured 63 ballot measures. Thirty-five measures (55.56%) were approved, and 28 (44.44%) were defeated. The decade with the highest approval rate was the 1960s, when 25 (86.21%) were approved, and four (13.79%) were defeated. Meanwhile, the decade with the lowest approval rate was the 1920s. This decade featured 44 ballot measures, of which four (9.09%) were approved and 40 (90.91%) were defeated.

The inventory of Arizona statewide ballot measures is part of Ballotpedia’s Historical Ballot Measure Fact Book, which will document nearly 200 years of direct democracy in the United States. This ongoing research effort will provide an unparalleled resource for researchers, reporters, and the voting public on how ballot measures have evolved, the issues they’ve covered, and the role they have played in our civic life.