Pulling together some 10 terabytes of raw data, including 1 billion sporting activities covering 27 billion kilometers over 200,000 aggregate years, Strava, which makes apps that allow users to track exercise and activity, put together an updated
global activity heatmap.
There's a
detailed blog covering some of the more unique and interesting plot points gathered from Strava users (the course for the marathon in Antarctica, Burning Man, the channel between England and France, the Ironman Kona Swim in Hawaii) that you should absolutely explore. For our purposes though, a quick zoom in on Northeast Ohio reveals a burning white necklace around Cleveland. That's the
Emerald Necklace (Cleveland Metroparks), of course, easily highlighted as the most active path(s) in the city.
Stretching southward is another white line, which would be the Towpath Trail.
Explore more for yourself here.