•  December 20, 2021

    Using Census Data and GIS to Answer Local Government Questions

    This article was originally published by Applied Geographics Inc. (AppGeo), a company acquired by The Sanborn Map Company Inc in September 2022.

    Synopsis: With the release of census data local governments have a massive amount of information to use and examine. But how can this data be most effectively used by local governments and what does it really represent?

    AppGeo is using our expertise in GIS to analyze and improve how local governments make sense of census data. This webinar (recorded on January 22, 2020) brings together Priya Sankalia, Project Manager from AppGeo, Bob Scardamalia, expert demographer and professor, Brianna Franklin, spatial IQ team member from AppGeo to discuss the ability of GIS to solve challenges facing local governments.                    

    What the Census Data Means

    Scardamalia: “One of the important things to remember about census data is they collect an awful lot of data. We tend to think of the census in terms of the decennial census, every ten years, and that is where people’s brains go when they think of the census. But there is a tremendous amount of additional data, not just demographic data but economic information. What I’m going to focus on today is the demographic side of the census. One of the most important things to remember is that the decennial census, every ten years, is only this very short list of data characteristics.”

    While the census provides a massive amount of information across the country, it is nonetheless a limited list of information about any given household. The information asked for is relatively basic, only concerning age, number of people, their relationship to one another, gender, race, and a few other basic factors. It does not provide detailed socio-economic data to local governments. However, the decennial census is supplemented by the American Community Survey, which is conducted yearly by the US Census Bureau since 2005. The American Community Survey does ask questions which have been left off the census, many of which concern socio-economic status specifically. It provides information on income, education level, language, disability, health insurance, cost of rent/home value, and more. 

    The other key to understanding how the census works is knowledge of how it divides up communities into census tracts. Census blocks, roughly equivalent to a city block but sometimes larger in rural areas, are areas bounded by geographic features. These 11 million census blocks are bundled into block groups, and then into census tracts. Census tracts contain roughly 4,000 people and represent a neighborhood or area. Every county in the US has unique census tracts. 

    Complicating all of this are political areas and statistical areas. Political areas are places with legal boundaries, elected officials, and governmental powers (law making etc.). Political areas can be a state, county, a city, town, reservation, or incorporated place. Statistical areas lack legal boundaries, elected officials, or specific governmental powers but they represent specific concentrations of population that are set by the Census Bureau to ease tabulation of data. Many times these areas are county based or town based. 

    2020 Census Data

    There are several sets of data that come from the 2020 Census and from the American Community survey. The Redistricting File is currently available and provides information about demographic changes that have altered political districts. The Demographic Profile, the Demographic and Housing Characteristics File, and the American Community Survey 5 year data (2016-2020) are all planned to be tentatively available in 2022. As mentioned previously, the American Community Survey is the most detailed of these, especially with regards to socio-economic information, whereas the others are mostly made up of basic demographic and population data. All of the available data can be found on Data.Census.Gov. 

    Spatial Analysis from Census Data 

    Franklin: “There are different data processing software [platforms] that you can utilize to be able to import census data files, which can be downloaded from the census website as Bob showed us. There are two really great data integration programs that we use that allow you to manipulate and merge datasets together with their spatial components, and those are Alteryx and FME… While these are the ones that we like to use, you can achieve this with other GIS softwares such as ArcGIS Pro.”

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