According to Spencer Overton, many states include prison populations for purposes of redistricting--even though as (mostly) convicted felons, they are (mostly) not allowed to vote. What's more, they're counted as residing in the district where they are incarcerated, rather than where they lived prior to incarceration.
The net effect is dilute voting strength in (mostly black) inner-city neighborhoods, and transfer that strength to white representatives in the rural counties which hold the prisons. One rural Nevada district includes a county where 95% of the black "residents" are in prison.
I concur with Alex Coolman--I am struck by parallels to the 3/5 compromise. For those of you lacking knowledge of this ignoble constitutional clause, the 3/5 compromise was the answer by the North and the South to the nagging question: How should slaves be counted in the federal census? The North wanted them counted for taxation but not representation. The South wanted them counted for representation but not taxation. And after much debate and discussion, they hit on the solution: Count them as 3/5 of a person both ways! And everybody was happy (except, of course, the slaves, but they're weren't really persons anyway--or at most 3/5 of one).
At least on face, however, this arrangement is worse than the 3/5 compromise (contextually, it isn't as bad since it isn't tied up with the slave system). It basically represents the Southern position--black prisoners are completely present for purposes of representation, even though they themselves are not allowed to choose their representatives. And, like in the "old days," these persons are placed inside their districts not by where they have chosen to live, but by where the powers-that-be have decided it most convenient for them to be placed. And wouldn't you know it? The arrangement just happens to be that black voter strength is sapped away by disenfranchised black persons, and transferred, vampire-like, to predominantly white districts electing white representatives who then (predictably) pass laws to put more black persons ("voters"?) into their prisons--thus strengthening their hand yet more. What a horrifically vicious cycle.
This may be a strained analogy, but I see parallels to the ID/Evolution debate here. You look at this system and how it so perfectly suppresses black people and elevates white power, while at the same time cloaking itself in the impenetrable armor of justice and righteousness, and you think: This must be designed. There is no way that such an incredibly complex, subtle, and effective method of preserving racial hierarchy could have come about naturally. But, good evolutionist that I am, I am ultimately swayed by the--in my view--scarier position. That these systems come into being not by a conscious design to keep black people in their place, but because our system is proactively racist when left on auto-pilot. If left to its own devices, without a conscious effort to correct, steer, and guide it away, our society will naturally and inevitably gravitate toward racist results. That's the way we, in our glorious color-blindness, work.
Personally, I oppose felon-disenfranchisement laws (especially for such bogus felonies as non-violent drug possession). But if we do have them, then prisoners should be counted as residents of where they lived as civilians--where their interests as citizens remain. The status quo completely strips prisoners of their personhood--which may, by itself, be a necessary incarceratory tool (I'm skeptical)--and then turns the dehumanized husk into slaves to the whims of the legislature; political pawns to be pushed around as line-drawing demands. You can't do both. You can't say that prisoners are no longer persons, and then re-create their identity into nothing more than a demographic tool. That is an unprecedented expansion of governmental authority to declare by fiat a polar shift in reality, a veritable deconstruction and reconstruction of what is to suit what the politicians want it to be. The state's power cannot justly extend that far.