The Census Bureau struck a blow for electoral fairness recently when it decided to speed up publication of its data on prison populations to ensure it is available for the next round of redistricting. We hope this new data, which will be released in the spring of 2011, will bolster the efforts of reformers who are trying to end prison-based gerrymandering  the cynical practice of drawing legislative districts with populations inflated by inmates who do not have the right to vote and whose actual residences are often far away.

Far too often, redistricting committees pad underpopulated districts by redrawing boundaries to include large prisons. This practice typically increases the political power of rural areas where prisons are built and diminishes the influence of the urban areas to which inmates eventually return. According to a study by the Prison Policy Initiative, a research group, in some counties the phantom prison constituents make up as much 20 percent of the population.

The decision to release the data early was taken at the behest of Representative William Lacy Clay, a Democrat of Missouri, who has long been concerned about the inequities brought by prison-based gerrymandering. The data will be especially helpful to the 100 or so counties that  at great effort  already remove prison inmates from the count at redistricting time. And it should give fresh impetus to legislation pending in several states  including New York  that would require them to determine the home addresses of inmates and draw legislative districts based on that information.

The Census Bureau still has to fix another problem: the failure to count prison inmates in their home districts. The questions for the 2010 census have been written already. The bureau should get to work on this problem with the aim of having it fixed long before the next count in 2020.