Technology for Boundary Delimitation

Technology can be a very effective tool for conducting electoral boundary delimitation, or redistributions of electoral boundaries. Powerful mapping technologies in particular, such as geographical information systems (GISs), as well as database software, can be used by election management bodies (EMBs) to assist with the boundary delimitation process.

The electoral boundary delimitation process can essentially be divided into two categories: determination of political boundaries (such as boundaries of parliamentary districts) and determination of administrative boundaries (such as boundaries of polling divisions).

Determination of political boundaries

Where political boundaries are being determined, there is often an element of "one vote-one value" included in the criteria for boundary distribution, as well as other more subjective criteria such as community of interests, means of communication and physical area. "One vote-one value" criteria generally require EMBs to ensure that either the number of people or number of enrolled electors residing in each district is within a specified range.

The process of drawing electoral boundaries that contain specified numbers of people or electors can be very complex, particularly where the permissible variation from the ideal quota is limited. The process can be complicated still further by requiring projected population growth to be taken into account. For example, for the Australian House of Representatives, a distribution of boundaries for the 51 districts in the State of New South Wales involves ensuring that the number of enrolled electors in each district is within 10% of the quota (or average number of electors in each district) at the time of the distribution, and that the number of enrolled electors estimated to reside in each district in 3 ½ years time is within 5% of the quota.

Technology can be used for this process by keeping track of the number of people residing in each parcel of land, and to allocate numbers of people to proposed districts which are made up of aggregates of parcels of land. "Point and click" boundary delimitation systems can allow EMB users to draw boundaries on computerised maps, which will then automatically calculate the numbers of people contained in each proposed district. This facility saves a great deal of manual calculation compared to "pencil and paper" systems of the past, thereby allowing EMBs to explore many more options than was feasible previously.

Technology can also be used to calculate population projections where distributions are required to take account of population growth rates.

Determination of administrative boundaries

Administrative boundaries are generally boundaries that are not linked directly to political representation on a "one vote-one value" basis. They can include boundaries of polling divisions, which are subdivisions of parliamentary districts that determine where individuals may vote. They can also include local government boundaries that are based on geographical or locality boundaries, rather than boundaries determined by numbers of residents, such as city councils.

Administrative boundaries do not tend to have strict criteria requiring specified numbers of people to be resident in each district. While there is less emphasis placed on determining numbers of residents in each district than there is with political redistricting, technology can still be used for the drawing of boundaries and with printing maps and other related output.

Passive and non-passive systems

It is possible to program boundary delimitation software to automatically draw boundaries according to the applicable criteria. This "passive" method takes the decision-making process away from people and relies on the instructions programmed into the software to produce a reasonable result. While the sophistication of GIS software continues to increase, computerised "passive" distributions are unlikely to produce boundaries that would be free from criticism, except in cases where the position of boundaries is of little importance.

Non-passive software allows the user to specify boundaries, and the software performs the necessary calculations to determine whether the criteria have been met. This method is most widely used as it allows users to draw logical boundaries using their knowledge of the process.

Passive systems can be combined with non-passive systems to provide a computer-generated starting point for users to manipulate as they see fit.

Applications of technology

Some examples of technology used for boundary delimitation purposes include:

• obtaining relevant data, such as demographic, political and geographic data 
• defining and manipulating census tracts, or defined geographical areas used for census purposes
• producing maps
• publishing results of boundary delimitation and results of elections following boundary changes
• using GIS to draw district boundaries
• using GIS to evaluate redistricting plans

Using GIS to Draw District Boundaries

Collecting the Necessary Information

Population Data

Maps

Synthesising the Information

Choosing Between Census and Election Geography

Drawing District Boundaries

Redistricting can be carried out using manual techniques - colour markers, paper maps, and calculators - or using sophisticated computers and geographical information systems (GIS) software. The technology employed does not change the task of the redistricters but it does change how the process is conducted and expands the information and options available to decision-makers when a final redistricting plan must be chosen. If GIS is to be used for drawing district lines, the first change in the process is the need to compile an electronic database.

Collecting the necessary information

Redistricting requires the collection of several different types of information. The two essential pieces of information are population data and maps. The population data, which may be in the form of census enumeration data or voter registration data, provide the only means of creating districts that are relatively equal in population. The population data must be associated with specific geographic areas and must be as accurate and up-to-date as possible. Maps are needed to ensure that only contiguous geographic population units are assigned to districts.

If the potential political impact of proposed redistricting plans is desired, then a third piece of information is necessary as well: political data. Political data may consist of statistics on the political party affiliation of electors, if available, as well as election results - tabulations of votes for candidates and ballot measures from previous elections by voting area. Including political data in the redistricting database allows line drawers to produce a political profile of proposed districts and to predict, to some degree, the partisan implications of a redistricting plan.

Election results can easily be entered into the redistricting database, if they are reported for the same geographic unit as the population data. This will likely be the case when the population units for redistricting are based on voter registration data. If, however, the population units are based on a census enumeration, the geographic units for population and political data may not be the same. In that case, census geography and election geography may have to be matched in some manner to create geographic units that can be associated with both population and political data.

Population data

Population data is essential to the redistricting process. Redistricting operates by combining discrete geographically-based units of population to produce districts of relatively equal population. The population data can be either total population counts based on a census enumeration or voter registration data; the geographic population units will therefore reflect either census geography or election geography (these units of geography are often, in fact, the same).

Traditionally the necessary population data has been collected and tabulated by hand. Recently, however, many countries have begun to computerize this data. If GIS software is to be used, population data (regardless of whether it is census enumeration or voter registration data) must be available in electronic form. Furthermore, each reported population count must be associated with a single unit of geography.

Maps

Maps are essential in the redistricting process, but obtaining adequate maps can be one of the most challenging obstacles facing redistricters. While standard maps, such as road maps, identify geographic features and the boundaries of administrative areas such as counties, cities and towns, they may not provide sufficient detail for drawing electoral districts.

If redistricting is based on a census count of the population, then the maps must show the boundaries of the census geographic units for which population statistics are available. If redistricting is based on the number of registered voters, then the maps must show the boundaries of the voting areas for which voter registration statistics are available. The boundaries of the existing electoral districts are usually needed as well as a beginning point for drawing new district lines.

In order to use GIS, software maps must be digitised and available in electronic form. Some redistricters have access to computerised maps because their governments have supported the development of uniform, digitised maps of the entire country and have chosen to make these maps available to redistricters. Digitised maps may be available from other sources, for example: local governments may have compiled digitised maps for transportation, health and other service planning or for land and resource management purposes; utility companies may have created digitised maps for service provision, network management or telecommunications purposes; or private companies may have digitised maps for fleet management, retail site location or for general marketing purposes.

If boundary authorities have access only to paper maps, digitised computer maps of the country can be created, but only at an enormous cost. Of course, these detailed computer maps can be used for many purposes other than redistricting and therefore may be worth the time, effort and expense.

Synthesising the information

If GIS software is to be used to redistrict, a redistricting database must be prepared once the necessary information has been collected. In an electronic redistricting database, spatial data is related to non-spatial information, such as population and demographic data. The spatial data must include the boundaries of the geographic units to be used as the basic building blocks for creating the districts. Population data must be related to each geographic unit. This data may be total population or the number of registered voters for each unit. Additional demographic data, such as population counts by race, ethnicity, religion or language-use for each unit may also be included if useful for redistricting. If the redistricting database is to include political information, then votes for candidates from previous elections should be entered for each geographic unit.

Choosing between census and election geography

Quite often census and election geography are one and the same and choosing between the two is not an issue. In some countries, however, census geography and election geography do not coincide and choices may have to be made. If voter registration data is to be used to create electoral districts, then election geography (for example, polling areas) may be employed as the basic building block for drawing district lines. This geography may correspond to the geographic units for which census data is reported, but it may not. If, on the other hand, census data is to be used, then the geographic units for which census data is reported is usually employed as the basic building blocks for redistricting.

If both census and election geography is available, and the two do not coincide, then the choice of which to use as the basic building blocks for redistricting often depends on who is making the decision. Election officials often prefer that election geography be used as the building blocks for redistricting, since they wish to avoid changing the existing system of voting areas as much as possible. Political parties and incumbent representatives may also wish to use election geography to create redistricting plans because political information is more readily obtainable for proposed district plans if the districts follow voting area boundaries. Regardless of which geographic unit is selected, if both political and census demographic data are desired, and election geography and the population geography do not correspond with one another, they will have to be matched. Matching census geography and election geography can be quite challenging.

Once a decision is made as to which unit of geography will serve as the basic building block for redistricting, a database can be created. This database is composed of spatial data reflecting the geographic units chosen as the basic building blocks, as well as other geographic information of importance such as administrative boundaries (for example, cities, towns, villages), and tabular data associated with these geographic units (for example, census counts and previous election results).

Drawing district boundaries

Once a database has been prepared, the next step in the redistricting process is the formation of districts. The line drawers create a redistricting plan either by assigning geographic units to districts for the first time or by moving geographic units in an existing plan from one district to another. A redistricting plan is complete when all geographic units in a given territory are assigned to a district and all districts in the plan meet the predetermined redistricting criteria. The geographic units to be assigned may be as large as counties or cities and towns, or they may be smaller units of geography such as census blocks or voting areas.

If the line drawers are to create a new redistricting plan by modifying districts in an already existing plan, their tasks may be relatively straightforward. This is especially true if a decision has been made that districts should be modified only as much as necessary to meet equal population standards. If there is no existing redistricting plan to modify or if the number of districts in an existing plan is to change substantially, however, the line drawers' tasks become more challenging.

The line drawing process is an interactive one; the redistricters assign a piece of geography and then determine how the inclusion of that particular geographic unit affects the size and composition of the district. Although aggregating the population totals for the districts after each new assignment is a straightforward process, it can be a tedious one as well. And as geographic units continue to be shifted, this process is repeated over and over again. A plan is completed and ready for evaluation when all geographic units have been assigned to a district.

Although this process has traditionally been done manually with an adding machine or a hand-held calculator, computers and GIS software can automate this process so that each time an assignment is made, the resulting map, population counts, and even political election results, are re-tabulated and displayed immediately on the computer screen. This allows redistricters to access the result of their assignments immediately. Redistricting plans can be created considerably faster and more efficiently and the results can be accessed much more accurately.

Using GIS to Evaluate Redistricting Plans

Many countries have instituted a set of formal rules, or criteria, for their boundary authorities to consider when drawing electoral districts. These redistricting criteria often include stipulations that districts should be as equal in population as possible, taking into account a variety of other factors. Administrative and/or natural boundaries and other geographic features such as sparsely populated or isolated territory are factors commonly listed. Respect for communities of interest  is another factor many countries specify. In some countries, especially developing countries, redistricters are asked to consider the means of transportation and/or communication as well. All of these criteria relate directly to the process of creating districts.

Another set of possible redistricting criteria relate to the outcome of the redistricting process—for example, requiring that district plans be drawn so that political parties are fairly represented or that racial, ethnic, religious or linguistic minorities have an equitable chance of representation. But countries that delimit districts usually do not adopt criteria relating to the fairness of the outcome. This is because countries with single-member districts can rarely meet these standards, if fairness of outcome is defined as proportional or near proportional representation for political parties and minority groups.

Regardless of whether the criteria relate to the process or the possible outcome, geographical information systems (GIS) software can often be used to measure compliance with these criteria.

Equal population

The most widely accepted rule for redistricting is that districts should be relatively equal in population. This is because representation by population is a central tenet of democracy and, in countries that employ single-member districts, this rule translates into the principle of equal populations across districts. Districts that are equal in population are necessary if voters are to have an equally weighted voice in the election of representatives. If, for example, a representative is elected from a district that has twice as many voters as another district, voters in the larger district will have half as much influence as voters in the smaller district.

The degree to which countries demand population equality varies. The United States is unique in its adherence to the doctrine of equal population. No other country requires deviations as minimal as the "one person, one vote" standard that has been imposed by U.S. courts since the early 1960s. New Zealand comes closest to that strict standard, with deviations of five percent or less from the electoral quota permitted.

Other countries, while recognising the importance of population equality, have chosen to balance this factor against other redistricting criteria perceived as equally valid. In the United Kingdom, for example, respect for local administrative boundaries is given precedence over exact equality of number. In many African countries, the need to recognise individual tribes may take precedence over population equality. Each country must determine how much variation from the ideal of exact population equality will be tolerated to accommodate other redistricting goals.

Summary reports listing the total population of each district in a redistricting plan is necessary to determine whether a particular plan meets the criterion of equal population, regardless of what level of adherence is required. If GIS software has been used to create the plan, a statistical report listing the population of each district, as well as the percent that district deviates from the population quota, is a very simple matter. An easyclick of the mouse will produce the needed report.

Geographic considerations

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 categories.

With regard to criteria related to geographic boundaries, for instance, a redistricting authority may be required to respect administrative boundaries such as county and municipality lines and/or natural boundaries created by dominant topographical features such as mountain ranges, rivers or islands. Factors such as the remoteness of a territory, the sparseness of population, or geographic accessibility are common examples of criteria related to geographic size. These factors are particularly important in countries which have large, sparsely populated territories, like Canada, Australia or Russia, or countries with islands or other isolated constituencies that are more difficult to serve. In addition, some countries require redistricters to take into account factors, such as whether the districts are geographically compact.

GIS software enables redistricters to produce maps of the newly created districts instantaneously. These maps allow redistricters to view the configurations of the newly created districts and to overlay administrative, political and natural boundaries onto the new district plan in order to access the degree to which these boundaries coincide with the new district lines. Often, not only is the map of the new districts instantly available, but statistics relating to the size and even the shape of the districts can be calculated and instantly reported. For example, some GIS packages can display the length or perimeter of a district in miles or kilometres as well as mathematical measures of geographical compactness.

Communities of interest

Because electoral districts are usually required to be relatively equal in population, single-member districts often do not reflect distinct geographic communities as signified by municipal, county or other administrative divisions. This does not mean, however, that political representation has been divorced from the notion of "community" in countries that redistrict—many countries that delimit single-member districts continue to emphasise the importance of creating districts that correspond as closely as possible to pre-existing communities, defined as administrative divisions and/or "communities of interest."

The rationale for recognising communities in redistricting is that electoral districts should be more than conglomerations of arbitrary, random groups of individuals. Districts should, as much as possible, be cohesive units with common interests related to representation. These shared interests may be the result of a common history or culture, a common ethnic background, or a variety of other ties that create a community of voters with distinct interests.

GIS software can be used to ensure that previously identified communities of interest are respected if the boundaries for these communities have been digitised and inserted into the redistricting database as a boundary layer. This may be a relatively simple task if communities of interest are taken to be administrative subdivisions, for example, or other regional or local communities that have well-established boundaries. This is more complicated, however, if the boundaries are not clearly defined.

Fairness for political parties and minority groups

Criteria specifying fairness for political parties and minority groups within a country focus on the electoral outcome, rather than the process, of redistricting. Electoral systems that rely exclusively on single-member districts, however, cannot guarantee proportional representation or even some minimal percentage of seats for minority political parties or for ethnic, racial, linguistic or religious minority groups in the population. This is because single-member districts inevitably produce disproportionately fewer seats for minority parties and minority groups, unless these groups are geographically concentrated in such a way that line drawers can create a proportionate number of districts in which these groups predominate, or special electoral provisions have been made to ensure certain minority groups some representation in the legislature.

Another approach to dealing with the inherent disproportionality of single-member districts is to adopt redistricting reforms designed to ensure a fair and impartial redistricting process. Reforms such as the adoption of independent, non-partisan commissions and neutral redistricting criteria do little to alleviate disproportional election outcomes, however. Taking the politics out of redistricting does not mean that a districting plan has no political effect—it simply guarantees that any political bias in a districting plan is unintentional.

Still another means of dealing with the potential political impact of a redistricting plan—and perhaps the most practical approach—is to attempt to determine the likely political implications of a proposed redistricting plan prior to enacting the plan. If political data (previous election results) have been included in the redistricting database, GIS software can use this information to make predictions regarding the likely political impact of a proposed redistricting plan. GIS software can do this by recompiling previous election results to conform with the newly proposed district lines.

Of course, simply being able to predict the likely political impact of a redistricting plan is not enough to ensure that a plan that is as fair as possible to all political groups will be adopted. Only if the redistricting authority is truly non-partisan or if all interested groups and citizens are armed with this information—and can therefore hold the redistricters accountable—can this approach succeed.

If a redistricting authority has a specific political agenda, sole access to this kind of information and/or sole discretion as to what plan to adopt, this information can actually result in a politically biased plan. This may be the reason that many redistricting authorities are not permitted to consider any political data at all when drawing district lines. However, it should be noted that political parties often have access to this kind of information, even if the redistricters do not, and may use this information to influence the boundary authority during the public hearing process. This is one example of why it is important to consider the context under which redistricting plans will be promulgated in deciding whether to use GIS or not.

Requirements for Using GIS Software for Redistricting

Requisites for the use of geographical information systems (GIS) software for redistricting can be divided into the following three categories: computer systems and software, spatial and other data, and users. In addition, a general understanding of GIS and the potential advantages and disadvantages of its use, as well as a frame of reference that permits its use, are important considerations in adopting GIS for redistricting.

Computer systems and software

GIS software runs on the whole spectrum of computer systems ranging from portable personal computers (PCs) to multi-user supercomputers. Regardless of what hardware system is chosen, a number of elements must be considered for the GIS software to operate effectively:

• the computer must have a processor with sufficient capacity (speed and RAM) to run the GIS software and sufficient disk capacity to store large volumes of data;

• a high resolution colour graphics screen to view the output;

• data input devices such as digitisers and scanners if paper data must be transformed into electronic data;

• data output devices such as printers and plotters.

Hardware requirements are both dependent on and determining of software requirements; hardware limitations may mean that particular software products cannot be utilised, while the availability of software can dictate what sorts of hardware must be purchased.

Software refers to both the operating system and specific application packages. GIS applications run in a variety of operating systems such as UNIX, Windows NT and Windows XP using GIS software programs such as Arc/Info, Intergraph, MapInfo or Maptitude or customised GIS software packages for redistricting.

Cost can be a key factor in the choice of hardware and software. Budgetary constraints, especially in many developing countries, limit the choice of which computer system and software can be used.

Data

Data includes both the cartographic database needed for using GIS applications as well as any accompanying attribute data (primarily population data in the case of redistricting). Data availability and accuracy—and especially the availability of digital cartographic data—are some of the most important requisites for the development of GIS capabilities. The extent to which GIS is used it is often dictated by the availability of digital cartographic data, or more often, the willingness to dedicate resources to creating such a database.

Many countries have produced a complete set of uniform, digitised maps covering the entire country, but others have only begun—or have not yet begun—this process.

Developing countries are faced with a number of limitations in the use of GIS applications that revolve around issues such as cost, training of specialized personnel, and data availability. As needs for resolving questions related to urban and rural land use, transportation, housing, and environmental pollution are emerging, there is a pressure to adopt GIS technology and to develop computerised maps which can then be adapted for use in redistricting.

Users

Users refer to trained personnel able to operate the GIS system. The main requisite for GIS users is the ability to work with computers to manipulate basic GIS software and databases as well as some general geographic and cartographic knowledge in order to be able to use GIS for redistricting.

Many GIS packages are difficult to use without proper training. The language barrier may pose an additional problem as many GIS manuals and programs—especially those designed specifically for redistricting—are written only in English.

Making the Decision to Use GIS for Redistricting

Countries contemplating the use of geographical information systems

 (GIS) for redistricting need to give careful consideration to the advantages and disadvantages of introducing a GIS. The reasons for adopting such a system need to be examined, and clear objectives identified.

Issues to be addressed include:

• expected benefits of introducing GIS

• improvement of the efficiency or effectiveness of the redistricting process

• availability of relevant maps

• costs of introducing a GIS for redistricting

• costs of obtaining additional maps

Potential GIS users may find it useful to conduct a thorough cost-benefit analysis to determine whether the expected benefits of adopting GIS for redistricting justify the anticipated costs of implementing and maintaining this technology.

Costs and benefits of using GIS for redistricting

Some of the direct costs that may be associated with the use of GIS for redistricting include:

• acquisition of computer hardware and software

• acquisition of customised software

• hardware and software maintenance and support

• data maintenance, including creating, editing and deleting data

• hiring of qualified personnel

• training staff

Some of the benefits that may be associated with the use of GIS for redistricting include:

• time saving for routine and repetitive tasks

• faster provision of information

• wider range of information provided

• more accurate information

• new range of output—maps, reports, etc.

• improved quality of redistricting decisions

Some costs and benefits—such as the cost associated with purchasing the GIS system and the time savings benefit—are relatively easy to identify and quantify. Other costs and benefits, however, especially indirect ones, are not as easy to identify and quantify but have to be taken in account when doing a cost-benefit analysis.

The cost of employing GIS for redistricting will vary dramatically depending on the availability of electronic data and the effort required to encode the data if it is not available electronically. If digitised maps of the entire country or of the region under consideration are available, the costs associated with adopting GIS can be expected to be more affordable. On the other hand, if a digital map data base has to be created, and the cost of this cannot be shared with other government agencies or organisations, the effort and cost required may not be worth the anticipated benefits of using GIS for redistricting purposes.

Choosing a GIS software package

Once the decision is made that expected benefits outweigh costs, the next step is to choose a GIS hardware and software.

Various options need to be analysed to determine which one will best meet the identified objectives. This includes deciding whether to develop the software in-house, to purchase a standard GIS commercial package, or to purchase a standard GIS software package and customise it (using in-house staff or consultants). Acquiring a standard, proprietary GIS system is likely to be cheaper, easy to use and well-supported by the provider, but may lack some of the required functionality identified for the specific redistricting exercise.

Some questions to consider when selecting a GIS software package include:

• hardware specifications required to run the software (processor speed and memory, disk storage capacity, storage capacity)

• operating system needed to run the software

• software ease of use

• documentation availability, quality and languages

• training availability

• software vendor market position (assurance of on going development and support)

• availability and cost of software upgrades

• software functions

• ability of software functionality to meet requirements

• extent of software package customisation to meet requirements

• software costs

In addition to researching these questions, a decision-making process may include benchmark tests and/or pilot projects with select GIS packages. For example, a benchmark test might be organised in which three or four GIS vendors are provided with a list of tasks that the potential buyer would like the GIS to be able to perform. The potential buyer might also supply data for use in the exercise. The vendors would then attempt to demonstrate that their system meets the potential buyer's requirements. This exercise requires a fair level of expertise and awareness on the part of the potential buyer, especially regarding the identification of the tasks to be performed by the vendors, but it may be well worth the effort.

Implementing GIS for redistricting

Once a GIS has been selected, it must be implemented. Even if there is nothing technically wrong with the GIS system chosen, problems may arise with its use depending on the how the system is implemented. Factors that could be important to the success or failure of the GIS implementation include:

• commitment to the use of information technology and digital data

• availability of experienced staff and/or consultants

• adequate training to enable staff to operate and support the system, including data entry, creation and maintenance of the GIS databases

• allocation of enough time and resources to create the databases and test the system extensively before being adopted

In addition to choosing the GIS package, ordering the necessary equipment and installing, implementing and testing it, the adoption of GIS technology for redistricting involves a complex interplay of technical and socio-political factors. Therefore, it is important to plan the implementation process carefully in order to ensure that the resources needed for the successful transition from the current to the new redistricting system are in place, that redistricting deadlines are met and that the redistricting plans produced are as accurate as possible.

This effort not withstanding, the risk remains that the optimal redistricting plan may not be created or selected.