Maricopa and Pinal counties are likely to gain political clout in the Legislature after new district lines are drawn -- at the expense of Pima County and much of the rest of the state, according to a new study.
The report by National Demographics Corp. being released Thursday points out that Pinal County has nearly doubled its population between the 2000 census and the latest projections. And Maricopa County is up by close to 31 percent.
Nowhere else in the state matches that.
What makes that important is the state is divided into just 30 legislative districts. And there is a legal requirement that all be roughly equal in population.
What that means is that lines will need to be redrawn to reflect where people are living now.
NDC president Doug Johnson said 19 of the state's 30 districts already are wholly or partly in Maricopa and Pinal counties. Johnson said that will have to go to 20 when the Independent Redistricting Commission meets beginning next year.
He figures much of that will have to come from Pima County. While the county grew by almost 21 percent since the decennial census, that hasn't kept pace with the statewide average of more than 28 percent.
Right now there are five legislative districts that are totally or partly in Tucson. A sixth district takes in rural portions of the western part of Pima County but the population base is in -- and the representatives are from -- Cochise County.
But Cochise County's population growth also has not kept pace with the rest of the state. Coconino County also is far behind the curve, as are Navajo, Santa Cruz, Graham, Gila, Apache and Greenlee counties.
Yavapai County has grown somewhat faster than the statewide average; Yuma and Mohave counties are slightly behind.
It will be up to the members of the redistricting commission exactly where to draw those lines.
Johnson said it's possible to configure any boundaries so that districts cross county lines. That might enable commission members to preserve Pima County representation, for example, by expanding a district to take in more of Pinal County.
One Pima County district already extends into the Saddlebrook area.
But there are limits to what the commission can do.
The Arizona Constitution requires the commission to create districts that are generally equal in size. The districts also must be "geographically compact and contiguous,'' must "respect communities of interest'' to the extent possible, and comply with the federal Voting Rights Act, which precludes changes that dilute minority voting strength.
How the changes might affect the political makeup of the Legislature is an open question in a state where Republicans outnumber Democrats.
That constitution requires that "to the extent practicable, competitive districts should be favored, where to do so would create no significant detriment to the other goals.'' But commission members, working with that constraint, were able to craft only four legislative districts where the registration is close enough between the two political parties to make it possible for candidates from either one to win.
Johnson said the latest census figures also show Arizona will pick up one -- and possibly two -- new congressional seats.
Here, too, the issue is one of relative growth: There are only 435 seats in then U.S. House; what Arizona gets will have to come from slower growth somewhere else.
"It's up in the air,'' Johnson said. "At this point I think Arizona is right on the razor's edge of getting two.''
One thing that may keep Arizona from getting that 10th congressional district is that the state's steaming growth rate of the early and middle part of the decade has slowed to a crawl: Between 2008 and 2009 the population increased by only 1.5 percent.
Here, too, Johnson said, the redistricting commission will have to consider relative population growth within the state in deciding how to allocate the new congressional strength.
He said if there is just one new district, the commission will need to accommodate the growth of Maricopa and Pinal counties.
"The big question there is whether there's a new Hispanic piece, or whether it's kind of put up in north Phoenix or the East Valley fast-growing areas,'' Johnson said, the latter choice which includes parts of Pinal County.
Johnson's firm was a technical adviser to the redistricting commission after the 2000 census. Johnson said this report was prepared without public funds, acknowledging he hopes his firm gets a contract to help with the new redistricting effort that begins next year.