How to Obtain Census Data for GIS Mapping

Sometimes new mappers are tripped up by census data, because in order to make a map, you need to download two separate census files:

1. A table of statistics
2. A geography boundary file

Sources

In this lesson, you will learn how to get these files from your choice of the following sources.

Social Explorer

• User-friendly
• Requires a license
• Access Social Explorer via Harvard Key

NHGIS.org

• Somewhat less intuitive
• No license required
• Access NHGIS.org for free

Either choice will provide you with census data well-tailored for GIS methods. We recommend using one of these sources for digital mapping, as opposed to downloading directly from The U.S. Census Bureau portal.

Example data

• We will be exploring tenure data, which looks at owner vs. renter-occupied units.
• We want census responses that have been aggregated to the census tract level.
• Our area of study is near the Harvard campus, in Somerville and Cambridge.
• We’ll be looking at the most recent estimates at the time this guide was written, 2015-2019.

Geography tip: Census tracts are a popular aggregation unit, as they are more granular than county or state level data, but more available and statistically-reliable than block level data.

The steps in this tutorial series will work for any U.S. census data, such as age, race, income, etc. If you’re not sure which variables are available, you can use censusreporter.org to find out.

Example of the tenure data we will work with, uploaded to ArcGIS Online.

Obtaining via Social Explorer

1. Visit your institution’s Social Explorer. Here is the link for Harvard’s Social Explorer.

2. If you have an account, log in. Otherwise, you’ll have to make one.

3. On the Social Explorer landing page, select Tables from the left-hand menu.

4. Since the housing variable is not collected in the full count every ten years, we need to refer the more detailed surveys collected of sample populations on a rolling basis, called the American Community Survey (ACS). Select American Community Surveys (5-Year Estimates).

5. Click Begin Report next to the 2015-2019 estimates.

6. Under Select a Geographic Type choose 140...Census Tract from the dropdown menu.

7. Under Select a State choose Massachusetts from the dropdown menu.

8. Under Select one or more geographic areas and click ‘add’ select All census tracts in Massachusetts.

9. Select Add.

10. Select Proceed to Tables.

11. Under Select one or more tables and click ‘add’ scroll down and select A10060: Tenure.

12. Select Add.

13. Select Show Results.

14. Navigate to the Data Download tab.

15. Under Download data by geography type select Census Tract data (CSV) and the tabular statistical data will download to your computer.

16. Under Download programs to import and label data select Data dictionary (text file) in order to interpret the dataset.

17. Close out of the report screen by clicking the X in the upper-left corner next to Create Report.

18. Now from the main menu, select Geodata.

19. Scroll down and select U.S. Tract 1910-2019.

20. Under TRACT 2019 US SL140 Coast Clipped select the button that reads Shapefile to download the GIS data you will need for mapping.

You are now ready to move on to the next skill, How to join data in QGIS.

Obtaining via NHGIS.org

1. Visit NHGIS.org.

2. Select Get Data.

3. Select Topics.

4. Select Housing.

5. Check off Tenure and Mortgage Status.

6. Finalize your topics selection by choosing the Submit button.

7. To specify we want to work with census tracts, select Geographic Levels.

8. Check off Census Tract.

9. Finalize your geographic levels selection by choosing the Submit button.

10. To indicate our time frame of 2015-2019, select Years.

11. Check off 2015-2019.

12. Finalize your years selection by choosing the Submit button.

13. Under Source Tables, check off the Tenure data table. This will add the census statistical table to our shopping cart.

14. To change the results that match our criteria from tables to GIS boundary files, select GIS Files.

    Remember, we need both!

15. Checkout by selecting Continue from the data cart in the upper-right hand corner of the screen.

16. Accept all of the download defaults.

17. Select Submit.

    You will need to create a free login in order to checkout. You can create one in a new tab if you don’t want to lose your data selection.

You are now ready to move on to the next skill, How to focus the data.

Tips

• It takes a few minutes to prepare your extract. You can either wait and refresh the page, or you will receive an email when the data is ready.
• Extracts come with any accompanying codebook.
• Use this codebook to make sense of the table’s field names.