diff --git a/static/js/history.js b/static/js/history.js
index fc1697b..1fce36b 100644
--- a/static/js/history.js
+++ b/static/js/history.js
@@ -33,7 +33,8 @@
 
     let _geoTimer = null;
     let _lastGeoKey = null;
-    let _geoCache = {};  // key → label, pre-populated on trip load
+    let _geoCache = {};
+    let _preloadController = null;
 
     function _geoKey(lat, lon) {
         const la = typeof lat === 'number' ? lat : parseFloat(lat);
@@ -43,16 +44,17 @@
     }
 
     function preloadGeocodes(points) {
-        // Pre-fetch geocode labels for all unique coordinates with a small
-        // concurrency cap so the server (which uses slow Nominatim) doesn't
-        // get overwhelmed. The Pi's reverse_geocoder is instant, so this
-        // still works fast there.
+        // Abort any in-flight preload from a previous trip selection.
+        if (_preloadController) _preloadController.abort();
+        _preloadController = new AbortController();
+        const signal = _preloadController.signal;
+
         _geoCache = {};
         const seen = new Set();
         const queue = [];
         for (const p of points) {
             const key = _geoKey(p.latitude, p.longitude);
-            if (seen.has(key)) continue;
+            if (!key || seen.has(key)) continue;
             seen.add(key);
             queue.push({ key, lat: p.latitude, lon: p.longitude });
         }
@@ -61,17 +63,18 @@
         const CONCURRENCY = 2;
         let idx = 0;
         function next() {
-            if (idx >= queue.length) return;
+            if (idx >= queue.length || signal.aborted) return;
             const item = queue[idx++];
             const ctrl = new AbortController();
             const t = setTimeout(() => ctrl.abort(), 3000);
+            signal.addEventListener('abort', () => ctrl.abort());
             fetch(`/api/geocode?lat=${item.lat}&lon=${item.lon}`, { signal: ctrl.signal })
                 .then(r => { clearTimeout(t); return r.ok ? r.json() : null; })
                 .then(data => {
-                    _geoCache[item.key] = (data && data.label) || null;
+                    if (!signal.aborted) _geoCache[item.key] = (data && data.label) || null;
                 })
                 .catch(() => { clearTimeout(t); })
-                .finally(() => next());
+                .finally(() => { if (!signal.aborted) next(); });
         }
         for (let i = 0; i < CONCURRENCY && i < queue.length; i++) next();
     }