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Mapping US Census Bureau Data with ArcMap

While the US Census Bureau makes a vast array of demographic and economic data available to the general public, that data is generally made available as tabular data. In order to map that data in ArcMap, you will need to join it to separately-distributed TIGER geospatial polygon files in order to map it. This tutorial covers those steps.

Table Download and Preparation

US Census Bureau data is made available through their data.census.gov open data portal.

For this example we will download the percentage of households in counties in Illinois with combined income of $200,000 per year or more from the DP03 table of the 2019 ACS five-year estimates.

  1. Go to data.census.gov and search for your variable of interest. In this case we look for the DP03 Selected Economic Characteristics table.
  2. Select the Product containing the variable. For this example we use the 2019 ACS five-year estimates. By default this will list values for the USA as a whole.
  3. Click Geos and select the geographical area you wish to cover. In this example we use all counties in the state of Illinois.
  4. Click Download to download a .zip file of the .csv information.
  5. Unzip the .zip archive and open the data_with_overlays CSV file in a spreadsheet program like Excel.
  6. Find the column for the variable(s) you want and remove the other unneeded columns. Leave the GEO_ID column that you will use for the join.
  7. Give the variable column a meaningful name with ten characters or less (in case you want to save as a shapefile).
  8. Look through the column and delete any cells that have non-numeric contents that could confuse ArcMap.
  9. If you haven't already, create a project folder
  10. Save As the file as a .csv with a meaningful name in your project folder.
Downloading and cleaning a table from data.census.gov

Polygon Download

The US Census Bureau data makes Cartographic Boundary Files from their Master Address File (MAF) / Topologically Integrated Geographic Encoding and Referencing (TIGER) database available as shapefiles that can be imported into ArcMap for mapping.

  1. Search for TIGER Cartographic Boundary Files to find the current download page.
  2. Download the zipped shapefile for the appropriate geography and year. In this case we use 2019 US counties and place the file in our project directory.
  3. Move the .zip archive to your project folder and unzip it to make the individual shapefile files available to ArcMap.
Downloading a TIGER cartographic boundary shapefile

Import and Join the Data

  1. Open ArcMap and create a new Blank Map.
  2. Click Add Data, connect to your project folder, and add the .csv table and the polygon shapefile.
  3. Right-click on Layers data frame in the Table of Contents, select Properties and Coordinate System, and change the projection to something appropriate like a World Mercator projection.
  4. Right-click on the shapefile and select Joins and Relates and Join....
    • For Choose the field... in the shapefile layer select AFFGEOID.
    • For Choose the field... in the table, select GEO_ID.
    • Choose Keep only matching records so the areas with no data are not displayed.
    • Click Validate Join to identify any problems.
    • Click OK when you are ready to join.
  5. Right click on the polygon layer, select Properties and Symbology and symbolize the polygons by the ACS variable.
  6. If the joined field is not displaying, check your Fields to make sure that the field was brought in as a number rather than text. If the field is text, it may have some non-numeric values that caused ArcMap to treat it as text. You can either go back to Excel and remove the offending cells, or use the field calculator to copy the data into a new column as text.
  7. If needed, add a base map and change the Display transparency to 30% so you can see the underlying base map for geographic context.
Importing and joining USCB data

Saving a New Shapefile

If you want to reuse your data in a new feature class to save you or your people the trouble of having to go through all this in the future, you can save the joined data as a new shapefile.

  1. Right click on the polygon layer and select Data and Export Data.
  2. Browse the Output feature class and give the name of the shapefile to save in your project folder.
  3. If you wish to conveniently share the new shapefile, create a .zip archive containing all shapefile files.
Saving a new shapefile