Ward redistricting assistance


Every ten years the US Census Bureau conducts a census of the
country’s population to see growth trends in different metropolitan
areas, migration patterns from one area to another, and changes in
demographics on the local, regional, and federal level. While this
census is conducted at the federal government level, local governments
use the population and demographic information to help with applying for
project grants, directing how and where to use certain funds for
capital improvements within the community and, for certain communities,
determining where to redraw voting boundaries to account for changes in
population number from one area to the next. For the City of Des
Plaines IL, redrawing the aldermanic ward boundaries was a top priority
once the 2010 census population numbers were released by the Census
Bureau due to upcoming alderman elections, with these boundaries
determining which areas of the city would vote in each ward. Since
these ward boundaries relate to city blocks and neighborhoods, the
city’s Geographic Information Systems (GIS) department was asked to
assist with calculating population statistics and developing scenario
maps for areas where the ward boundaries would potentially change based
on population shifts between the 2000 and 2010 census.

To make sure the new ward boundaries divided the city up into
relatively even population bases, several boundary scenarios were mapped
to provide city administrators with a visual tool for comparing the new
boundaries against one another. In addition to visually displaying
the ward boundaries, population numbers for each new ward area were
calculated and provided along with the maps, which provided both a
visual and statistical tool for analyzing each ward scenario. The
population information for each ward map was calculated at the
neighborhood block level using GIS census boundary data provided by the
Census Bureau in conjunction with a table containing related population
information for each block. By using the block level data, each ward
boundary could be drawn as accurately as possible to ensure that each
ward contained a relatively even number of city residents. Since this
information was provided by the census in a digital, spatial format, the
process of drawing a new ward boundary and running the population
numbers was relatively easy, allowing for numerous boundary scenarios to
be calculated quickly and provide city administrators with a wide range
of boundary options to consider.

Using GIS resources to assist with the city’s alderman ward
redistricting effort, the City of Des Plaines was able to save a
significant amount of time and money as compared to if the process was
completed without it. Without GIS, according to information provided by
city administration, the process would have taken several weeks of
dedicated city staff time to complete or, if the city would have instead
used an outside vendor, and additional monetary investment of $25,000.
By using an available, existing resource, the city was able to save
money and staff time and dedicate internal resources to other tasks
rather than focusing on manually calculating the new ward population
numbers and drawing the new boundary locations.