On June 4, Democratic Governor J.B. Pritzker signed a state legislative district map drawn and approved by the Democratic majority in the legislature. The Senate and House minority leaders have in turn sued to have the map overturned in federal court on account of the data that was used for balancing population between districts was census ‘survey’ estimate data (from the American Community Survey (ACS)), and not the hard count data historically used for redistricting. Read the complaint here.
The controversy stems from the months-long delay in delivery of redistricting population data by the Census Bureau due to the Covid-19 public health emergency, which delayed execution of the census during the Spring of 2020. The complaint lays out the unsuitability of using ACS data for redistricting purposes:
“Because it uses ACS estimates for population data, the Redistricting Plan does not ensure that the Senate and Representative Districts satisfy the constitutional mandate of substantially equal populations. The Redistricting Plan fails to ensure substantial population equality for a number of key reasons:
a. Unlike the decennial census, which represents a complete count of the population, the ACS estimates represent a small sampling of addresses and are therefore subject to sampling errors and imprecision, which can be considerable for small geographic areas and population groups;
b. The ACS single-year estimates are available only for geographic areas with populations of 65,000 or more, and the five-year ACS estimates, which are the only available estimates for more sparsely populated geographic areas, are based on outdated survey responses dating back more than five years before the census date and fail to fully represent
population changes that have occurred since that time;
c. Unlike the decennial census, which is supported by substantial federal, state, and local funding for public outreach campaigns, the ACS receives far less funding and has a lower response rate, which creates further imprecision;
d. The ACS estimates are not available for each individual “Census Block” but are instead reported in larger “Census Tracts” or “Block Groups” (depending on the particular estimates) and must be manipulated to
attempt to fit the applicable Census Blocks; and
e. The ACS estimates are based on the 2010 census geographic boundaries
and must be manipulated to fit the updated 2020 census boundaries.”
