diff --git a/assets/static/js/modules/map-manager.js b/assets/static/js/modules/map-manager.js
index e3438e8..3149e51 100644
--- a/assets/static/js/modules/map-manager.js
+++ b/assets/static/js/modules/map-manager.js
@@ -199,7 +199,12 @@ export class MapManager {
         
         legend.innerHTML = '';
         
-        for (const [id, source] of this.sourcesData) {
+        // Sort sources alphabetically by name
+        const sortedSources = Array.from(this.sourcesData.values()).sort((a, b) => 
+            a.name.localeCompare(b.name)
+        );
+        
+        for (const source of sortedSources) {
             const item = document.createElement('div');
             item.className = 'legend-item';
             item.innerHTML = `
diff --git a/assets/static/js/modules/ui-manager.js b/assets/static/js/modules/ui-manager.js
index 8db8301..9bb8618 100644
--- a/assets/static/js/modules/ui-manager.js
+++ b/assets/static/js/modules/ui-manager.js
@@ -226,8 +226,12 @@ export class UIManager {
         // Clear options except "All Sources"
         select.innerHTML = '<option value="">All Sources</option>';
         
-        // Add source options
-        for (const [id, source] of this.sourcesData) {
+        // Sort sources alphabetically by name and add options
+        const sortedSources = Array.from(this.sourcesData.entries()).sort((a, b) => 
+            a[1].name.localeCompare(b[1].name)
+        );
+        
+        for (const [id, source] of sortedSources) {
             const option = document.createElement('option');
             option.value = id;
             option.textContent = source.name;