How Do I Start Thinking About Redistricting in My Locality?

If you are new to redistricting, you might begin with reviewing the current district plan or considering the number and nature of the districts to be created. You might also want to familiarize yourself with the process that is used to choose or adopt an official redistricting plan. You may find that the group deciding which plan is best is intimately concerned with the outcome as it effects their own districts. In other instances, independent commissions, advisory commissions (which may be comprised of legislators, non-legislators or a mix thereof), or even courts may have the ultimate decision power. Incumbency is often a factor in redistricting even if the incumbents are not deciding the outcome.

At its core, a redistricting plan or solution is an allocation of census blocks or larger levels of geography to districts. These census blocks (defined in greater detail later) may include all those blocks in a census tract, neighborhood, precinct, town, or city. Generally, redistricters aim not to split smaller political subdivisions. So, for example, districts for a county board of supervisors will often keep towns in separate districts rather than splitting them apart in multiple districts. In general, it is important that there be roughly equal numbers of people in each district. For national congressional redistricting, house districts must be balanced to within a single person. For state and local districts, the permitted differential from perfect balance will be higher, and it will vary by jurisdiction.

A color-coded and labeled map showing the districts and their populations is a convenient way to display a redistricting plan, but an Excel file listing the census blocks in each district would be sufficient for an exact definition. In fact, any listing of the official IDs of the blocks in each district would be enough. A plan will have district population totals that can be compared with the target population and will thus have measurable deviations from the ideal balance of population. It is important to know the maximum deviation that is legally acceptable for the redistricting solution that you are working on.

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