Places with a greater population tend to get more representatives in a state or federal legislature, all else being equal.
This makes sense for minors (part of voter-households) and noncitizen adults (either another part of voter-households or with freedom of travel) but it becomes a perverse-incentive when we start talking about people forced to be in a specific place by a government that put them there and won't let them leave.
> Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons
"Free persons" in this case meant those not enslaved for life, so it includes incarcerated people. Representation apportionment also includes illegal immigrants under this clause.