First, until a redistricting bill, regardless of its format as will be discussed below, is dropped in the hopper, the same privacy restrictions likely apply as to any other bill. This is important, especially when large draft maps may be available for viewing by members—but must be secured. At the very least, draft maps must be developed in a locked facility where your plotter is secure.
Redistricting plans begin as maps. Each map, and all its content, is typically translated into a bill. The legislature then votes on the bill. How the map is created, what data is used, and the language used in the bill can be quite different based on the type of approach used to represent the real world. In most cases, states use one of the following: “metes and bounds” information, geographic information system files called shapefiles or block equivalency files.
Traditionally, “metes and bounds” have been used to describe the physical world. Metes and bounds is a system to describe a piece of land, or in the case of redistricting, a district. With the metes and bounds approach, specific real-world geographic features, and occasionally jurisdictional boundaries, are used to identify the boundary of a district. This system is still common.
The bill to enact a redistricting plan includes a street file. Street files often look like this:
300 – 500 Main Street, even numbers |
Senate District A |
House District 11 |
301 – 501 Main Street, odd numbers |
Senate District A |
House District 12 |
502 – 750 Main Street, even numbers |
Senate District B |
House District 11 |
As you can see from the example above, street files are tabular in nature, with additions being added as a spreadsheet of some kind is edited. Additions are made over a decade, between redistricting years. The maintenance of this list can be particularly challenging since additions cannot be viewed spatially. Also, if there is an error in translating geography into a list, it will likely not be identified. The list is what is signed into law.
Another approach used to represent the physical world is the shapefile. A shapefile is a data format used in geographic information systems (GIS) software. A shapefile is a combination of several files and data sets. One file (.shp) defines geography, such as legislative districts, congressional districts, and Census geographic units (block, block groups, tracts, etc.). Another file (.dbf) contains attributes for each geographic unit, such as the total number of persons, the voting age population, and the racial composition of the population in each geographic unit (as per the Census data). Other files included in a shapefile are necessary for the proper use of the shapefile, such as shape index (.shx) and projection (.prj) files.
Geographic features in a shapefile can be represented by points, lines, or polygons (areas). Because shapefiles maintain the correct spatial, or topological, relation among the different geographic units, they are ideal for redistricting purposes. For example, shapefiles allow for the addition or subtraction of geographic units into districts to achieve population equality, compactness, contiguity and other redistricting principles.
A shapefile is a combination of two or more data sets: one that defines geography (per the census), one that defines population (also per the census) and perhaps others. By dividing all territory into unique shapes, no terrain is missed, and new developments will fit within a pre-defined shape.
A redistricting bill can refer to, and include, a shapefile. It is important to note that shapefiles are a good way to represent physical geography; however, they must be updated and managed appropriately. Election data scale needs to be at a particular level to place voters in the right district. This scale needs to be determined by a GIS professional—hence the importance of election and GIS professionals working together.
A third option is the block equivalency file. A block equivalency file is a table that provides a one-to-one correspondence between census blocks and districts. Because all geography is captured in a census block, by accounting for all census blocks, all geography is included in a district. By going this route, it is less likely that any voters will be assigned to the wrong precinct. ("According to Election Data Services, every time they perform a voter verification process in a jurisdiction, between 10 and 12 percent of voters are currently in the wrong precinct, although many fewer are in the wrong electoral districts.)
Census block 1
|
House District 13
|
Senate District 1
|
Census block 2
|
House District 13
|
Senate District 2
|
Census block 3
|
House District 14
|
Senate District 2
|
Census block 4
|
House District 15
|
Senate District 3
|
The decision about how to define the maps in legislation is likely to be made by leadership, but staff may be called on to explain the options and make recommendations. In a few states, statute will call for one option or another, and legislation would be needed to change to a new system.
Transmitting Redistricting Plans to Local Election Officials
Once redistricting bills are enacted, the legislature’s work is done—but the work for local jurisdictions is just beginning. Local election officials need to define precincts and prepare voter lists based on who is in which district, from U.S. House, through state districts, and down to special districts. The hand-off of data to the local jurisdictions can make their work easier or harder. And, with the next election likely just a few months away (and filing deadlines even sooner) they don’t have a lot of time for this task.
It is likely local election officials have a street address file that corresponds to all known addresses in the county or other jurisdiction that might look something like this:
300-600 Main St (even addresses)
|
District 13
|
Precinct 13A
|
301- 601 Main St (odd addresses)
|
District 13
|
Precinct 13B
|
1-12000 East First Place
|
District 14
|
Precinct 14A
|
1-12000 East Second Place
|
District 14
|
Precinct 14B
|
In the past, common practice has been to update that file, rather than start from scratch. That may be changing this decade, as interest in using GIS in the general field of election administration increases.
In states where metes and bounds are used for legislation, the translation to a street address file is difficult.
In states that use shape files from their GIS systems that depict the geometry and data associated with districts, election administrators need to be able to work with GIS as well.
If possible, transferring the districts to administrators through a block equivalency file—where every census block is detailed—is preferred. With thousands of census blocks, it’s still hard. It might be helpful to discuss the transfer process with your state’s local election officials well in advance.
Detailed maps of new district boundaries and reports of the existing precincts included in, or split by, new district lines may also be helpful to provide to local election officials.
In addition, local jurisdictions may be preparing to do their own redistricting for county, municipal, school board or other electoral bodies. While they have their own processes and criteria, they will want to start with the state’s map.