How Trail Names Are Generated
The trail names that appear alongside the trails on the map are actually pre-rendered map tile images. These tile images are generated and then cached for each zoom level to increase load time and performance.
The app has always used these image labels, but at various times, the website has used labels generated in vector text by Mapbox. The generated labels are of a much lower quality and are MUCH less frequently drawn. So we choose to use the tile image based labels that look better, display better, and are more frequently shown, despite them consistently updating as you zoom in or out of the map.
How Image Labels Are Cached
There are several levels of caching. The CDN (Content Delivery Network) caches the tile for 6 days; meanwhile, our server caches the tile for 6 days. In effect, it's possible that with the correct overlap timing, it could take up to 12 days to refresh the trail label text.
When a trail is updated, the system sends a bounding-box to the tile server, telling the server to update all tiles in this area. The server is not typically able to handle all these requests as the requests are resource intensive. Instead, these requests go into a queue that gets slowly worked on, one request at a time. The queue is often several thousand items long, so updates can take several weeks to complete.
Your local browser cache may also be working to cache tile images. The local browser cache shouldn't cache longer than 6 days, since the header maximum is set to this limit.
If your trail label text on the map isn't updating accurately, we recommend clearing the app from running on your device, (exiting out), and then re-opening the app to see if the map is loading accurately.