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Census Bureau Releases Detailed Data for New Legislative Districts

By Kelley Griffin  |  March 30, 2023

The 2020 census is in the rearview mirror, new congressional and legislative districts have been drawn just about everywhere in the nation, and the first elections have been held using those new boundaries. That’s all old news.

The new news is that, for the first time this decade, the winners of those legislative races can get detailed data on their districts from the U.S. Census Bureau’s American Community Survey, or ACS. The bureau released a special product for the new 2022 legislative districts on March 16, based on the 2017-21 ACS five-year estimates. There’s more detail on those districts to come when the 2018-22 ACS estimates are released later this year.

“We want to help our colleagues understand their districts better. The new data products are very useful.”

—Massachusetts Sen. Will Brownsberger

Wendy Underhill, NCSL’s director of elections and redistricting, says the data will help legislators better understand whom they serve. “The district name and number may have stayed the same, but with boundaries moved during redistricting, each legislator has at least some new communities and constituents now,” she says.

The official once-in-a-decade census is the bureau’s premier product, and it provides the data used for congressional reapportionment and for redistricting. The ACS is a different product altogether.

“When you work for the Census Bureau, you are inevitably asked, ‘What do you do the other nine years? Are you just sitting around waiting for the next census?’” Gretchen Gooding, chief of the outreach and education branch of the ACS office, said with a chuckle during a recent NCSL webinar. “That is, of course, not true. The data collected through the ACS is used to help inform the distribution of hundreds of billions of dollars in federal funds each year.”

Going Deeper

Unlike the decennial census, which aims to count every person in the land, the ACS is based on a sample and provides a much wider array of data. 

“Our social characteristics include topics like disability status, educational attainment, language spoken at home,” Gooding says. “Our demographic characteristics are much like those used for the census: age, sex, race, Hispanic origin,” although ACS data goes deeper. “Our economic characteristics include topics like commuting to work, employment status, income, health insurance. And our housing characteristics include topics like computer and internet use, plus housing costs and the number of vehicles available.”

To effectively use such a massive amount of data, lawmakers, legislative policy analysts and others have to learn a thing or two about it. To that end, the Census Bureau’s team of data dissemination specialists offers free training to anyone interested in exploring the American Community Survey website and other bureau resources.

The Population Reference Bureau, a private international research firm, also helps users get started. “You can use [this data] to learn where and how to best serve your constituencies,” says Alicia VanOrman, the firm’s senior research associate. “With it, you can identify disparities between different population groups and geographic areas or look at trends over time or, for example, examine the effects of the COVID-19 pandemic.”

Once how to use it has given way to why to use it, states have answers. Karin Mac Donald, the director of the California Statewide Database and veteran data master for redistricting and much more, says that while the decennial census is the main source for redistricting decisions, the ACS offers critical details that help meet requirements of the federal Voting Rights Act.

She cited the Citizen Voting Age Population, or CVAP data, which is the estimated number and percentage of people who are both over 18 and U.S. citizens and thus eligible to vote, broken out by location, race and ethnicity. The CVAP for California showed, in one example, that over a span of 10 years, one county went from 55.4% white CVAP to 47.3% white CVAP. “This all reflects how California’s population changes,” Mac Donald says. 

Protecting Communities of Interest

Mac Donald says it is critical in redistricting to create districts that take communities of interest into consideration as well, so that those communities are not inadvertently divided and can be effectively represented. Often, ACS data is just what’s needed to do that.

“ACS data does provide color to the official redistricting data, the decennial census, but that’s not all it does for elections,” Underhill says. “It also is the official source of data used to determine, per federal law, where around the nation voting assistance materials must be produced in languages other than English.”

The Texas Legislative Council uses ACS five-year estimates extensively. For instance, it posts district profiles and graphics to member webpages for its 31 state Senate and 150 state House districts. Legislators use these easy-to-access products to assist with constituent questions. The council also responds to member requests for all kinds of demographic and statistical information, whether through tables, maps or graphics—and the answers are often based on ACS data.

Then there’s policymaking, which is increasingly driven by data. Patrick Dean, the assistant director of Alabama’s Commission on the Evaluation of Services, says the ACS is vital to his work. 

“We regularly use ACS data to compare how our state compares to other states, regions and nationwide, and locally on a range of topics,” Dean says, noting the commission maintains a website to share those comparisons. 

The Tennessee House of Representatives relies on ACS data to map policies, says Adam Bryant, the chamber’s GIS coordinator. “Recently I’ve been doing a lot of crime analysis across the state of Tennessee.” The ACS data tables helped with his analysis by providing not only population data at the census tract level, but also median household income at the same level.

“This data has helped with correlating poverty levels to crime rate in smaller geographies across the state,” Bryant says. “Oftentimes whole counties can get a bad reputation, but when you’re able to drill down to these smaller geographies, it helps paint a better picture.”

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