From an article earlier this summer on prison-based gerrymandering, a comparison to the 3/5 Compromise:
Characterizing it as a modern-day 3/5ths Compromise, [former ACLU attorney Michelle] Alexander explained that in most states census residence rules require that incarcerated people be counted at their place of incarceration as opposed to their home address.
She went on to explain that the overwhelming majority of incarcerated people in the United States hail from the major metropolitan centers of this country while the prisons are typically built in non-urban or rural areas. This counting practice results in a shift in population from urban center to rural community thereby increasing the political clout of rural communities while decreasing the political clout of urban communities.
When prison-based gerrymandering is employed, district boundaries redrawn to align with census figures results in large portions of what would have been urban population being reapportioned to rural counties.
Because of this practice, urban communities, particularly urban communities of color stand to lose the most. Census figures help determine where government money will go to fund hospitals, school services, public housing, social services, food stamps and other programs. The census figures are also used to determine how many seats each state has in the U.S. House of Representatives. Prison-based gerrymandering may result in the loss of both federal dollars and political representation for districts that are already struggling.