If your figure contains one or more traces of type go.Scattermapbox, go.Choroplethmapbox or go.Densitymapbox, the layout.mapbox object in your figure contains configuration information for the map itself. The map is composed of various layers, of three different types:

1. layout.mapbox.style defines is the lowest layers, also known as your "base map"
2. The various traces in data are by default rendered above the base map (although this can be controlled via the below attribute).
3. layout.mapbox.layers is an array that defines more layers that are by default rendered above the traces in data (although this can also be controlled via the below attribute).

The word "mapbox" in the trace names and layout.mapbox refers to the Mapbox.js open-source library, which is integrated into Plotly.py. If your basemap in layout.mapbox.style uses data from the Mapbox service, then you will need to register for a free account at https://mapbox.com/ and obtain a Mapbox Access token. This token should be provided in layout.mapbox.access_token (or, if using Plotly Express, via the px.set_mapbox_access_token() configuration function).

If your layout.mapbox.style does not use data from the Mapbox service, you do not need to register for a Mapbox account.

The accepted values for layout.mapbox.style are one of:

• "white-bg" yields an empty white canvas which results in no external HTTP requests
• "open-street-map", "carto-positron", "carto-darkmatter", "stamen-terrain", "stamen-toner" or "stamen-watercolor" yeild maps composed of raster tiles from various public tile servers which do not require signups or access tokens
• "basic", "streets", "outdoors", "light", "dark", "satellite", or "satellite-streets" yeild maps composed of vector tiles from the Mapbox service, and do require a Mapbox Access Token or an on-premise Mapbox installation.
• A Mapbox service style URL, which requires a Mapbox Access Token or an on-premise Mapbox installation.
• A Mapbox Style object as defined at https://docs.mapbox.com/mapbox-gl-js/style-spec/

Here is a simple map rendered with OpenStreetMaps tiles, without needing a Mapbox Access Token:

import pandas as pd
us_cities = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/us-cities-top-1k.csv")

import plotly.express as px

fig = px.scatter_mapbox(us_cities, lat="lat", lon="lon", hover_name="City", hover_data=["State", "Population"],
                        color_discrete_sequence=["fuchsia"], zoom=3, height=300)
fig.update_layout(mapbox_style="open-street-map")
fig.update_layout(margin={"r":0,"t":0,"l":0,"b":0})
fig.show()

If you have access to your own private tile servers, or wish to use a tile server not included in the list above, the recommended approach is to set layout.mapbox.style to "white-bg" and to use layout.mapbox.layers with below to specify a custom base map.

If you omit the below attribute when using this approach, your data will likely be hidden by fully-opaque raster tiles!

Here is an example of a map which uses a public USGS imagery map, specified in layout.mapbox.layers, and which is rendered below the data layer.

import pandas as pd
us_cities = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/us-cities-top-1k.csv")

import plotly.express as px

fig = px.scatter_mapbox(us_cities, lat="lat", lon="lon", hover_name="City", hover_data=["State", "Population"],
                        color_discrete_sequence=["fuchsia"], zoom=3, height=300)
fig.update_layout(
    mapbox_style="white-bg",
    mapbox_layers=[
        {
            "below": 'traces',
            "sourcetype": "raster",
            "source": [
                "https://basemap.nationalmap.gov/arcgis/rest/services/USGSImageryOnly/MapServer/tile/{z}/{y}/{x}"
            ]
        }
      ])
fig.update_layout(margin={"r":0,"t":0,"l":0,"b":0})
fig.show()

Here is the same example, with in addition, a WMS layer from Environment Canada which displays near-real-time radar imagery in partly-transparent raster tiles, rendered above the go.Scattermapbox trace, as is the default:

import pandas as pd
us_cities = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/us-cities-top-1k.csv")

import plotly.express as px

fig = px.scatter_mapbox(us_cities, lat="lat", lon="lon", hover_name="City", hover_data=["State", "Population"],
                        color_discrete_sequence=["fuchsia"], zoom=3, height=300)
fig.update_layout(
    mapbox_style="white-bg",
    mapbox_layers=[
        {
            "below": 'traces',
            "sourcetype": "raster",
            "source": [
                "https://basemap.nationalmap.gov/arcgis/rest/services/USGSImageryOnly/MapServer/tile/{z}/{y}/{x}"
            ]
        },
        {
            "sourcetype": "raster",
            "source": ["https://geo.weather.gc.ca/geomet/?"
                       "SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX={bbox-epsg-3857}&CRS=EPSG:3857"
                       "&WIDTH=1000&HEIGHT=1000&LAYERS=RADAR_1KM_RDBR&TILED=true&FORMAT=image/png"],
        }
      ])
fig.update_layout(margin={"r":0,"t":0,"l":0,"b":0})
fig.show()

Here is a map rendered with the "dark" style from the Mapbox service, which requires an Access Token:

token = open(".mapbox_token").read() # you will need your own token

import pandas as pd
us_cities = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/us-cities-top-1k.csv")

import plotly.express as px

fig = px.scatter_mapbox(us_cities, lat="lat", lon="lon", hover_name="City", hover_data=["State", "Population"],
                        color_discrete_sequence=["fuchsia"], zoom=3, height=300)
fig.update_layout(mapbox_style="dark", mapbox_accesstoken=token)
fig.update_layout(margin={"r":0,"t":0,"l":0,"b":0})
fig.show()

See https://plot.ly/python/reference/#layout-mapbox for more information and options!