As the cluster of prisons in southern Ada County continues to grow, the county's population of prisoners has also grown. The Idaho Correctional Center, now the state's largest prison, added some 1,500 residents to legislative District 21, which was already flush with prisoners a decade ago.
The problem is that those residents don't vote, mostly come from other parts of the state and are disproportionately from poor and minority areas.
Now in full swing, the 2010 Census will only boost the non-voting population in District 21 and in Idaho's First Congressional District, giving voters there a disproportionate amount of influence.
Peter Wagner of the Prison Policy Initiative calls it prison-based gerrymandering.
"If you pad the prison districts with prisoners, your district gets physically smaller because you need less people," Wagner said.
Wagner has bugged the U.S. Census Bureau about this flaw since he did his law school independent study on prisoners and redistricting in 2000. He's hoping for changes in the count in 2020, but he and a growing group of demographers have convinced the Census Bureau to at least release the prison count sooner, before redistricting efforts kick off.
Census Bureau spokeswoman Shelley Lowe said that the bureau counts people in their "usual residence" and it's up to the states to figure out how to factor that into redistricting.
"This decade we are releasing early counts of prisoners ... so that states can leave the prisoners counted where the prisons are, delete them from the redistricting formulas, or assign them to some other locale," Census director Robert M. Groves blogged.
In Southwest Idaho, Wagner said that if prisoners cannot be counted where they lived before they were incarcerated, it would make sense to gerrymander the prison complex into multiple districts.
"It reduces the magnitude of the vote enhancement, it reduces the harm," he said.