Queen Creek, Buckeye and Florence saw the largest population increases this year, according to new figures from the Arizona Office of Economic Opportunity.

On paper, the town of Queen Creek grew by more than 9,000 residents between July 1, 2017, and a year later. That's enough to conclude an astounding 22.5 percent year-over-year growth.

But Jim Chang, the state demographer, points out that virtually all of the growth on the Pinal County side came from the community annexing already existing development. If you subtract out those instantly acquired 5,277 residents, the percent is 9.4 — still the highest in the state, but not quite as eye-popping.

Why Do Annexations Matter?

Population figures are used to divide up some forms of state aid. The final say lies with the official census figures, but the state’s annual estimates provide an indication of who will be winners and losers.

Political power is also determined by population figures.

Arizona is divided into 30 state legislative districts, each of which is supposed to have roughly equal population.

If some areas of the state grow faster than others, the lines have to be redrawn, and areas that don't keep pace with the average will share their state senator and two representatives with an ever-larger geographic area.

At the current pace, Maricopa and Pinal counties are set to pick up more lawmakers after the 2021 redistricting.

Other 2018 Annexations

Sahuarita, a town to the south of Tucson, logged an annual growth rate of 5.3 percent.

Nearly half of the 1,526 new residents didn’t move from somewhere else — their development was reclassified from an unincorporated area.

Even Tucson took advantage of the idea of annexing existing developments, Chang said, picking up 3,960 instant Tucsonans along with another 1,911 due to natural growth.

Those annexations showed up on the other side of the ledger, Chang noted, with the population of unincorporated area of Pima County shrinking by 1,810 despite new developments.

Where Are People Settling?

Buckeye recorded the second highest percentage growth. Located on the far west side of the Phoenix area it has annexed large swaths of vacant land that are suitable for development.

As those working in the Phoenix area look farther out for affordable housing, that boosts some other communities.

Florence grew 6.3 percent year over year. But Chang said at least some of this is due to an updated figure on the number of people in area prisons.

Population Declines

On paper, the town of Clifton lost 307 people and Greenlee County as a whole shrank by 455.

But Chang said there was a change in methodology in doing the estimates, as prior efforts failed to adequately take into account the rapid growth since 2010 following the reopening of the Freeport McMoRan mine.

He said there was no actual year-over-year decline in population.