In many countries, the electoral laws specify that geography, or certain geographic factors, be taken into account when delimiting electoral district lines. Geographic criteria can be divided into two categories--criteria relating to geographic boundaries and criteria relating to geographic size and/or shape. A boundary authority may be asked to consider factors from either or both criteria.
Criteria Related to Geographic Boundaries
Respect for clearly established boundary lines is often specified as a criterion for those redistricting to consider when drawing electoral district lines. These boundaries can include administrative boundaries such as county and municipality lines and/or natural boundaries created by dominant topographical features such as mountain ranges, rivers or islands.
Perhaps the most commonly mentioned geographic factor listed by countries is consideration for local administrative boundaries. Dozens of countries list this as a criterion to consider including: Albania, Bangladesh, Barbados, Bulgaria, Cameroon, Canada, Croatia, Czech Republic, Fiji, France, Germany, India, Indonesia, Italy, Japan, Kenya, Lithuania, Malaysia, Mexico, Pakistan, Panama, Tanzania, Uganda, United Kingdom, and Yemen. Botswana’s Constitution specifies consideration of not only administrative district boundaries, but the boundaries of tribal territories.
Another geographic feature commonly listed is population density or sparseness of population. Several Caribbean countries as well as Kenya, Mauritius, Nepal and Papua New Guinea identify this as a factor to take into account when redistricting. In Malaysia, the Election Commission is required to weight sparsely populated rural constituencies in a manner to guarantee their over-representation in the legislature.
Geographic redistricting criteria such as respect for administrative boundaries and physically defined natural communities are a higher priority in some countries than in others. In the United Kingdom, for example, respect for local administrative boundaries and natural communities is the most important concept guiding boundary commissioners. Large population disparities are tolerated as a result.
Criteria Related to Geographic Size and Shape
Two other factors that are sometimes listed as redistricting criteria relate specifically to the geometric shape of a district: contiguity and compactness. Advocates of these criteria hold that districts should not be oddly shaped and that all pieces of a district should be inter-connected. The election commission in Mexico, for example, is required to create electoral districts in which the perimeters are regular in shape. Other countries that specify that constituencies be compact include Albania, Armenia, Bangladesh, Barbados, Belarus, Dominican Republic, India, Italy, Pakistan, and the United States.
In the United States, district compactness has not been required by federal law since 1929, but when a number of states created some bizarrely-shaped districts in the1990s round of redistricting, the U.S. Supreme ordered the redrawing of a number of these districts. Although the shape of these districts was not actually the basis for the Court's decision, the fact that the districts were not compact was considered evidence of an impermissible motive in creating the district boundaries. (For additional discussion of these court cases see Role of the Courts in Electoral District Delimitation.)
