Upload Census Data to Felt

The goal of this tutorial is to start with a spreadsheet of census information, and upload the information so that it displays as polygons on the map. As mentioned in the software requirements section of this workhop, we are choosing Felt as a venue to get started working with census data because it faciliates the process of table joins for us.

Table joins work in Felt because Felt has already pre-uploaded vector geometry files of different census geometries. Felt includes these data layers because mapping census data is a common GIS task. An example would be a default layer of all of the county shapes in the United States. Another example would be a default layer of the shape of every census tract in the United States. To remind yourself of the different options for census geographies, you can refer to the census geography hierarchy documentation on census.gov.

For any of these data layers, for example, census tracts, each census polygon will have a unique ID associated with it. These ID codes are sometimes called GEOIDs or census FIPS codes. When we are uploading a spreadsheet with data we want to map, it is important to make sure the spreadsheet has a column with a corresponding unique ID. The column does not have to be called “GEOID”, but it does have to contain the same unique strings indicating which census geography any given table row pertains to.

To upload census data to Felt, make sure

• Your dataset is organized by geography, meaning, each row in the dataset represents one census geography (either a county, a census tract, a block group, and so forth, depending on which geographic unit you’ve chosen to aggregate by).
• Your dataset has a column containing the census geography GEOID code.
• Your dataset has a column you’d like to map. If the column contains numerical statistical values, ensure the column is formatted as a number type.

This table is formatted so that it will display as polygons in Felt. The GEOID column will join with the pre-uploaded census tract shapes, which come as a default with Felt.

Upload instructions

It’s important to make sure Felt knows which column to use for geography. There are lots of different ways to turn a tabular spreadsheet into a map. For instance, you can

• Transform a table of x,y coordinates into points
• Locate the centroid of a place name and represent it as one singular dot on the map

We don’t want to choose either of those options. We want to map our data as polygons, because having the polygon shapes will allow us to shade each unique region with a different color to visualize population density. To play around with different graduated color schemes, check out the mapping website Color Brewer .

GEOID	County	Pct_Nonwhite
1400000US36001000100	Albany County	66.7994687915007
1400000US36001000201	Bronx County	84.2596348884381
1400000US36001000401	Kings County	10.7779226423294

Notice how in the table above, there is both a column for GEOID (the field we would use to join our data to matching polygons), and a column listing which county each census tract is contained by. If we uploaded a dataset like this to Felt, there is a chance Felt could trying to use the County field to treat as the spreadsheet geography, and instead of joining the GEOID field, it would place the data as dots on the map representing county centroids.

To avoid this and ensure your census spreadsheet data will join up with census polygons, it’s best to do some pre-processing cleaning of your spreadsheet, and remove any redundant geography columns you don’t need for your map.

Steps

Upload

1. Remove all columns from the table besides the GEOID and the field you want to map. You can also leave in any information you want to show up in a pop-up window, for instance the fields you used to derive your mapped columns. This might help you explore the data in more detail later.

2. In a Felt map, from the top-menu, select Upload Anything.

3. Choose Upload file.

4. Select the spreadsheet you have prepared.

5. To the prompt “How do you want to add this data?” Choose Data Layer and Create.

6. Wait for the data to upload. There is a progress bar in the Legend.

7. When the data finishes uploading, you will know it was successful if you can see polygon features on the map.

Symbolize

1. Right now the polygons are all showing up the same. To use graduated symbology, click the layer in the Legend.

2. This will bring up a sidebar on the right. The first item in the sidebar will be the title of the layer, which is created from the filename. If you are happy with this title, proceed to the next step, but if you’d like to change it, you can click on the title text in the sidebar.

3. Under Style → General → Type, change Simple to Color Range.

4. Under Color by, ensure Felt is identifying the correct variable to map, if not change the name of the field using the dropdown.

5. Under Polygons → Fill you can change which color ramp to use.

6. Click General → Steps. This will open a menu that lets you control how your data are grouped into categories. Click the value next to Method and explore how you want to bin your data.

If you choose Jenks or Equal Interval, for instance, you can define how many binning categories to use. If you choose Manual, you can set the ranges yourself.

Configure popups

1. Under Popups → Contents, click Table.

2. You can remove attributes from showing up in the popup window, or change the field alias for how field names display.

Add a histogram

1. To add a histogram to your Legend, from the menu bar, select Components.

2. In the configuration menu that pops up on the right, ensure the correct Attribute is selected. These histograms are interactive; you can use them to change which polygons are displayed on the map.