Add Context to Your Map with Reference Layers
Add custom overlays to your DistrictBuilder map.
Context is key when drawing a redistricting map. In DistrictBuilder, the Reference Layer feature gives you the ability to add a layer to your map to provide additional context about communities of interest, incumbent locations, or any other features you think are relevant to your map.
You can use the reference layer to tell more about the story of your map. For example, if you want to make sure you are recognizing Native American lands — not only with demographics but that your boundaries respect and keep those communities whole. Or, you may want to overlay a neighborhood of community of interest reference layer to avoid splitting them unnecessarily. Finally, maybe you have a layer of incumbent residence locations and want to make sure you aren’t moving them out of their district (note that this is sometimes not allowed to be considered!).
Add, removing and labeling a reference layer on the map
Layers must be in GeoJSON or CSV format. If you have a shapefile, convert it to GeoJSON on this website or use your own tool. GeoJSON files must be smaller than 25MB. If your GeoJSON file is too large, you can use Mapshaper to simplify it. The GeoJSON can be polygon or point geometry.
To add a GeoJSON reference layer, click the Reference Layers panel beneath the district list on your map. Then, click Upload layer.
Drag and drop your CSV/GeoJSON or click Browse files to select a location on your hard drive.
If your upload is successful, you’ll see this screen indicating how many features are in your reference layer dataset. Give it a name and choose a field from the data that you want to label. In this case, we’re adding a layer of municipalities with its own label field.
Click Add to map and the layer will display on the map! This may take a few moments for large or complex files.
Now with the layer on the map, you can toggle it on or off using the checkbox next to the name. If you want to remove the layer, click the ellipse and choose Remove from map.
Adding a CSV as a reference layer
If you have a CSV of incumbent locations or other point data, you can upload that to the map as well. Note that the CSV must have degrees latitude and longitude coordinates in separate fields, like the example below:
What about map sharing? When you share a map, your reference layer will still be available to display. If you copy or duplicate a map with reference layers, you’ll also have access to that reference layer.
Reference layers with organization templates
With our organization page feature, you’ll have the extra bonus of including reference layers automatically when someone creates a page with your organization’s template. If you are interested in an organization page for your redistricting efforts, contact us today.
