How to use a line layer as a background map

There may be situations where your map only contains some regions, and it can be difficult for a user to identify where these regions are located. In this case, you can use our line layer in the Projection map template to add an outline of a wider region as a background map. This is also a great choice to create a light-weight map that loads quickly across different devices.

In the example below, our Regions layer contains English counties colored in blue. Here, we've added a line layer with the outline of the UK that helps the user contextualize what part of the world they are looking at.

    Begin with one of our Projection map starting points, or upload your regions to the blank map, and set a Value binding to color your regions.

    TIP: When uploading your own GeoJSON, we recommend file sizes up to 5 MB. Anything larger than that will reduce performance. To learn how to resize your GeoJSON file, head over to this help doc.

    Go to the Lines tab and upload the wider region that you want to use as a background map. You can upload GeoJSON containing polylines, polyons and multipolygons to the line tab. In this case, we used a GeoJSON of the whole of the UK.

    TIP: If you don't have a GeoJSON at hand, you can copy the geometry from any of our map starting points.

    Add the Geometry binding to your lines sheet and your outline will appear on the map.


    If your Lines layer sits outside the bounds of your regions, you may need to toggle the Include lines data option under Projection in the settings panel.

    Now go to the Lines layer settings, where you can change the style of your background map line. Here, you can customize the color, width, opacity, and dash-style. 
    Read more about the lines layer in our help doc.

Get started with your own Projection map now! »