There are usually two phases in the electoral district delimitation process. The first phase is the allocation, or apportionment, of seats in the legislature to regional entities such as states or provinces. This is usually a very mechanical process, with the number of seats assigned to each state or province usually dependent on the relative population of that state or province. In countries that do not delimit single-member districts, the reallocation of seats, or reapportionment, is the only step taken to equalize population across electoral districts.
In countries that do redistrict, the second phase of the process is usually the adjustment of the boundaries of current districts and/or the creation of new districts within the states or provinces themselves. In countries that do not allocate seats regionally, this is the only phase in the process.
Drawing electoral district boundaries is much less mechanical and much more time consuming than allocating seats. It proceeds in three stages:
- preparation of a redistricting database
- assignment of geographical units to districts until all units have been assigned and the boundaries of all districts established
- production of a summary description and maps for evaluating and implementing the redistricting plan
