Add a polygon to a map using a GeoJSON source | Mapbox GL JS

This example adds a polygon to a map, then colors it blue and makes it slightly transparent.

Upon loading, the map uses addSource to add GeoJSON data containing one polygon that outlines the state of Maine. Then it uses addLayer to create a new fill layer and applies paint properties to style the polygon's appearance. To add an outline around the polygon, it uses addLayer again to create a new line layer referencing the same GeoJSON source.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Add a polygon to a map using a GeoJSON source</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v2.14.1/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v2.14.1/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
	// TO MAKE THE MAP APPEAR YOU MUST
	// ADD YOUR ACCESS TOKEN FROM
	// https://account.mapbox.com
	mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
const map = new mapboxgl.Map({
container: 'map', // container ID
// Choose from Mapbox's core styles, or make your own style with Mapbox Studio
style: 'mapbox://styles/mapbox/light-v11', // style URL
center: [-68.137343, 45.137451], // starting position
zoom: 5 // starting zoom
});
 
map.on('load', () => {
// Add a data source containing GeoJSON data.
map.addSource('maine', {
'type': 'geojson',
'data': {
'type': 'Feature',
'geometry': {
'type': 'Polygon',
// These coordinates outline Maine.
'coordinates': [
[
[-67.13734, 45.13745],
[-66.96466, 44.8097],
[-68.03252, 44.3252],
[-69.06, 43.98],
[-70.11617, 43.68405],
[-70.64573, 43.09008],
[-70.75102, 43.08003],
[-70.79761, 43.21973],
[-70.98176, 43.36789],
[-70.94416, 43.46633],
[-71.08482, 45.30524],
[-70.66002, 45.46022],
[-70.30495, 45.91479],
[-70.00014, 46.69317],
[-69.23708, 47.44777],
[-68.90478, 47.18479],
[-68.2343, 47.35462],
[-67.79035, 47.06624],
[-67.79141, 45.70258],
[-67.13734, 45.13745]
]
]
}
}
});
 
// Add a new layer to visualize the polygon.
map.addLayer({
'id': 'maine',
'type': 'fill',
'source': 'maine', // reference the data source
'layout': {},
'paint': {
'fill-color': '#0080ff', // blue color fill
'fill-opacity': 0.5
}
});
// Add a black outline around the polygon.
map.addLayer({
'id': 'outline',
'type': 'line',
'source': 'maine',
'layout': {},
'paint': {
'line-color': '#000',
'line-width': 3
}
});
});
</script>
 
</body>
</html>