How to Import and Visualise GeoJSON Layers in Google My Maps

Geographic Information System (GIS) analysts, urban planners, and logistics coordinators frequently rely on GeoJSON—an open, human-readable standard based on JSON—to store geospatial coordinates, boundary polygons, and point attributes. While Google My Maps natively supports KML, CSV, XLSX, and GPX uploads, it does not provide an immediate, direct file picker option for raw .geojson files. By understanding file conversion methods and attribute formatting workflows, users can seamlessly import GeoJSON geometries into Google My Maps to build interactive spatial visualisations.

Understanding GeoJSON Structure and Google My Maps Limitations

GeoJSON structures spatial data through explicit geometry types—including Point, LineString, Polygon, and MultiPolygon—encapsulated inside feature collections:

• Geometry coordinates: Expressed as longitude and latitude decimal pairs (e.g., [-0.1278, 51.5074] for London). Note that GeoJSON places longitude before latitude, matching spatial cartesian planes.
• Properties dictionary: Houses associated tabular attributes (such as site name, postal code, elevation, or category classification) corresponding to each spatial shape.

Because Google My Maps enforces an ingestion schema tailored to Keyhole Markup Language (KML) and tabular spreadsheets, feeding unstructured or overly complex multi-megabyte GeoJSON collections directly into the interface results in parsing failures. Transforming raw GeoJSON into structured KML or flattened CSV datasets preserves shape geometry while maintaining layer compatibility.

Converting GeoJSON to KML or Formatted CSV

Before importing your dataset into Google My Maps, convert the .geojson file using one of the following reliable tools:

1. Using ogr2ogr (GDAL) via Terminal

For large geospatial datasets, the command-line GDAL utility provides the most accurate and lossless format conversion:

ogr2ogr -f "KML" output_boundaries.kml input_features.geojson

This command extracts all feature properties, translates GeoJSON coordinate arrays into standard KML placemarks, and retains polygon vertex coordinates intact.

2. Using Open-Source Web Converters

If command-line tools are unavailable, use browser-based cartographic platforms like geojson.io or mapshaper.org:

1. Navigate to the mapping utility and drag your .geojson file onto the workspace.
2. Inspect the geometry preview to confirm coordinate alignment and projection accuracy (WGS84 / EPSG:4326).
3. Click Export and select KML or CSV.

Importing the Converted Layer into Google My Maps

Once you have generated the converted KML or CSV file, upload it into a dedicated My Maps layer:

1. Open a web browser, navigate to Google My Maps, and sign in with your Google account.
2. Click Create a New Map (or open an existing saved project).
3. In the map legend panel on the left, locate the default layer and click Import.
4. Drag and drop your converted .kml or .csv file into the upload dialogue window.
5. If uploading a CSV file, Google My Maps will prompt you to select the columns representing location coordinates (choose Latitude and Longitude) and the column specifying placemark title labels.

Google My Maps will immediately parse the coordinates, centre the viewport over your bounding coordinates, and render all points, polyline paths, and boundary polygons across the base map.

Customising Layer Styling, Data Tables, and Icons

Raw spatial imports often default to uniform blue map markers or unshaded polygon outlines. Customising visual styling highlights patterns across your geographic zones:

1. Hover over the imported layer title in the left legend panel and click Individual styles.
2. Select Group places by:
   • Uniform style: Applies identical colours and marker shapes across all placemarks on the layer.
   • Sequence of numbers: Automatically numbers map markers sequentially to illustrate routes or inspection steps.
   • Categories by column: Groups placemarks according to an imported attribute column (such as district status or facility type), assigning distinct colour swatches to each unique value.
3. To adjust polygon fills and outlines:
   • Click directly on a polygon boundary on the map or select its name from the layer list.
   • Click the Colour bucket icon to adjust interior fill transparency and border line thickness.
4. Click the Open data table menu icon (three dots beside the layer title) to edit tabular property attributes, delete rogue coordinates, or append descriptive notes without re-uploading the dataset.

Exporting and Sharing the Collaborative Map

Once your GeoJSON data is styled, click the Share button on the legend panel to configure viewer permissions. You can generate a shareable web link, embed the interactive map into corporate intranets via iframe markup, or re-export the entire curated project as an enriched KMZ package.