Drew University – Spatial Data Center Geographic Information Systems 2014-2015 Tutorial, EPA TRI University Challenge

Google Fusion Tutorial: Combining NATA and US Census Geospatial Data

This tutorial buildings on the previous tutorial that explores NATA data, to combine US Census data with NATA information:

 Obtaining and Editing Data from the US Census  Merging Fusion Tables  Mapping and Summarizing Fusion Tables

Part 1: Obtaining and Editing US Census Data

The US Census provides detailed and comprehensive information on demographic characteristics across the US. In the previous tutorial that examined NATA data, US census tracts were used to display information about differential environmental health impacts associated with air pollution. Detailed census tract information on demographic characteristics of each tract, can be obtained from the US Census Website.

Step 1: Download and Edit Risk Data

Though there are many different ways to obtain population data from the US Census website, this tutorial will use the American Fact Finder web application. First, visit the American Fact Finder website.

Click the Download Center tab, and suppose that you know the data that you want. I know that I want data on the demographic characteristics of New Jersey census tracts. I want to use 2000 Decennial Census data, the SF1 files that describe the general racial and ethnic composition of those census tracts. After selecting the characteristics that describe my criteria for census data, American Fact Finder should look something like the screen shot below.

When you click next, a prompt to download your file will appear. Save the file, then double click on the file to extract it (described in previous tutorial), and you will have the census data files that you need. Double click the .csv file that includes _with_ann at the end of the title. It should open automatically in Excel.

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Delete the first header row the codes for each census variable, and save the file again, as a .csv (Comma Separated Values) type.

Part 2: Creating Google Fusion Tables

To access Google Fusion Tables, you need to first have a . These are free. Once you have a Google Account, visit http://drive.google.com to log into your site. Click Create > Connect to More Apps. Type in Fusion Table, and connect to the Fusion Table app.

Select Create > Fusion Table. Navigate to the .csv file that you saved, then click Next >>, Next >>, and finish (it may take a few minutes, so be patient).

Part 3. Merging Google Fusion Tables

The next step is the merge the spatial data polygons to the table with information about risks for each census tract. Click File > Merge, and choose to merge with the spatial data file (in this case, you can use the file that you created in the previous NATA tutorial). Then, change the merge field to Id2 for the table, and FIPSNO for the spatial data file. Click Next, and choose to merge all the columns, then view the table that’s created.

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Part 4. Mapping with Google Fusion Tables

Click the Map tab to see the polygons for the census tracts again. Now, you can edit to map to illustrate differences, based on the data in the tables. Click “Change feature styles,” and then under Polygons, click Fill color (this will allow you to choose the colors and data to map). For example, click the Gradient tab, and click the button to “Show a gradient.” Change the column to a variable of your choosing, such as “Percent Hispanic” (in image below). Click the “use this range” button. You can select the

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number of classes, and the color range for each class (if you use the “Buckets” tab, you can also select the specific range for each color).

You can also change the style info window to change the information that’s displayed. The files contain a “description” field that is useful for displaying a summary of the information.

Part 5. Filtering Google Fusion Tables

One the upper left hand corner of the map is an option to filter the data. Data can be filtered by any of the fields (or columns). One useful application for filtering is by examining values in specific ranges. For example, for New Jersey, total cancer risks of over 0.000085 fall into the top decile (or top ten percent) of the state’s census tracts. By clicking filter, and entering the range for the top decile, the map will then be altered to show only the values falling within that range (examples shown in image below).

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All files that you work on in Google Drive are saved as you work with them. However, it is useful to edit the name, which you can do by just clicking the title on the page, and renaming the file. At this point, you can share the fusion tables, the map, or both. To just share the map, click tools > publish, and copy the link to email or share in a website. For example, here is my map: https://www.google.com/fusiontables/embedviz?q=select+col2%3E%3E2+from+1MvgH4pF- YwHSKi7P07d5fJJLGRFKHEWd0xdb_p- S+where+col12%3E%3E1+%3E%3D+0.000085+and+col12%3E%3E1+%3C%3D+0.00013&viz=MAP&h=false&lat=40.76312 4868878705&lng=-74.00625053955082&t=1&z=11&l=col2%3E%3E2&y=2&tmplt=2&hml=KML

To share the Fusion Table, click the “Share” button in the top left of the screen. You can change who can access the file, if you like. For example, my fusion table is shared as a public link on the web: https://www.google.com/fusiontables/DataSource?docid=1MvgH4pF-YwHSKi7P07d5fJJLGRFKHEWd0xdb_p-S

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