Why does a GPS track show a different trail than the one you actually hiked?
Two things can cause this, and they are not the same problem. One is ordinary GPS position error landing your track a few metres from where you actually stood, which matters most exactly where two trails run close together — a switchback stacked above itself, a spur branching off the main line, an old route and its replacement sitting side by side. The other is that the trail lines drawn on the base map underneath your track come from a separate dataset that is not always current, so a trail can be redrawn or closed on the ground long before the map catches up. Your recorded line can be perfectly accurate and still look like it is on the wrong trail, because the trail it is being compared against is the one the map still has, not the one that is actually there.
The short answer
A GPS track and the trail lines drawn underneath it come from two different places. Your track is a string of coordinates your phone logged as you walked. The trail on the map is separate line data, drawn from a map dataset maintained independently of anything your phone recorded that day. Most of the time the two line up closely enough that nobody thinks about the difference. Where two real trails run within a few metres of each other, or where the map still shows a trail that has since been rerouted, that gap becomes visible — your track can drift onto the neighbouring line, or sit exactly where you walked while the map insists that spot belongs to a different, no-longer-current trail.
When it is ordinary position drift
Every GPS point carries a small amount of position error, typically a few metres, present on every walk regardless of how careful the recording was. On open ground with nothing else nearby, that error is invisible — there is no second trail for it to land on. Where a switchback doubles back on itself, where a shortcut path runs parallel to the main trail a short distance away, or where two legs of a route pass close to one another, that same handful of metres of ordinary drift is enough to make a point recorded on one trail appear to sit on the other. Nothing went wrong with the recording; the two trails were simply closer together than the everyday margin of error the position data already carries.
When it is the map, not the track
Trail lines on a map are not automatically updated the moment a trail changes on the ground. A rerouted switchback, a washed-out section replaced by a new line, or a social trail that has become the path most people actually use can all exist for a long time before the map dataset is edited to match — someone has to notice the change and redraw it by hand, and that can lag well behind reality. Until that happens, the map keeps showing the old trail exactly where it always was. A track recorded on the new, correct path can then look like it has wandered off the trail, when what actually happened is that the trail moved and the map has not caught up yet.
Telling the two apart
- A track that drifts back and forth between two trails over a short stretch, rather than sitting consistently on one or the other, points to ordinary position error — accuracy wanders point to point, it does not relocate permanently.
- A track that sits consistently and smoothly on a line the map does not show as a trail at all, for the whole distance you actually walked it, points to the map being out of date rather than anything wrong with the recording.
- Checking the spot afterward on a different, more recently updated map — or against a recent trip report for that trail — is a more reliable way to settle which one it is than staring at either line alone.
Either way, the fix is not something to look for in the recording. A stray point from ordinary drift is not worth correcting, and an outdated trail line on a map is not something a hiking app can fix on its own — that correction happens on the map data itself, usually by someone submitting an update once the change on the ground is confirmed.
Where TrailCam fits in
TrailCam draws your recorded route as a line on the map exactly as the GPS receiver logged it, with photos, video clips and voice notes pinned to the point on that line where you captured them. If a stretch of trail looks off from what the base map shows, exporting that route as a GPX 1.1 file lets you compare it against a different map or share it with whoever maintains the trail data for that area. GPX export is part of the optional TrailCam Pro upgrade; the app itself is free to download.
Questions
- Does my track showing on the wrong trail mean the GPS recording was bad?
- Not necessarily. It can be ordinary position error of a few metres landing on a trail that happens to run close to the one you were actually on, which is a normal margin present on every recording, not a sign of a failed one.
- Why does my track sit on a trail that no longer exists?
- Trail lines on a map come from a dataset that is updated by hand whenever someone notices and records a change, which can lag well behind a reroute or closure on the ground. Your track can be accurate while the map underneath it is simply showing an older version of the trail.
- Can a hiking app fix an outdated trail line on the map for me?
- No — the trail lines are separate map data maintained independently of the app, not something a recording app edits. The fix is on the map dataset itself, usually made once someone submits the change for that specific trail.
Recording your own routes
TrailCam is an iPhone app that records your route with GPS, keeps video clips, photos and voice notes pinned to the spot where you took them, and exports the result as GPX 1.1 or CSV. It is free to download.