For brevity, I'll write throughfare instead of 'route', because I ask NOT only about vehicular roads, but also nature paths, trails, waterways, etc...
On Google Maps, how can I highlight the entirety of a throughfare (eg the Bruce Trail in Ontario, Canada)? For example, I wish to thicken the length and width of its depiction on the map, and to intensify its colour. To wit, I seek something like this:
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