Yes. iPhones don't show an automatic "Install" button. If you want the app on your Home Screen, you can add it manually using Safari / Share / Add to Home Screen.

Most of the time, yes. But iPhones sometimes remove the app automatically if the device is low on storage or hasn't used the app in a while. When this happens, the app icon stays on your Home Screen, but the app may need an internet connection to reload its files before it can work offline again. This is normal behavior on iOS and affects all web-based apps.

Android treats this app like an installed app. Once you install it, Android saves everything it needs directly on your device for offline usage. The app stays installed and keeps working, with or without internet.

For the most reliable offline experience, an Android device is recommended. Android keeps the app stored on your device after you install it, so the map and all offline features remain available even after long periods without internet.

The app also works on iPhone, but iOS may remove the app's stored files automatically if the phone is low on storage or hasn't used the app in a while. This is standard behavior for web-based apps on iOS. If the files are removed, the app may need an internet connection again to reload them.

The PCT and AT trail maps are digital maps in the KMZ file format.

That's a lot of apps. You can use the maps in free apps like the Map Viewer app, or in free geobrowsers like Google Earth Pro on desktop. There are many others. We don't lock you into using a specific app, map, device or operating system.

Red diamonds on the maps are mile markers. The distance between two red diamonds is one mile. Red diamonds are labeled with elevation.

No. The free trail maps are free trail maps. The free app is a free app. No required registration or sign-ups.

Yes, the PCT and AT is centered on each map.

Each PCT and AT map is a custom 1:24,000 scale topographic quadrangle covering an area of approximately 49 to 56 square miles.

The 1:24,000 scale provides detailed information about the natural and manmade features of an area that are usually omitted from maps in the 1:50,000 to 1:100,000 scale range.

The PCT and AT maps are custom quadrangles that include detailed topographic base maps at a 1:24,000 scale. Each page is centered on the trail and overlaps with the adjacent pages. In this way, one trail map can cover the detail that is found on up to four different USGS topographic maps. BLM and state land boundaries are included on the PCT maps.

The PCT and AT maps overlap where the trail enters (or exits) each map. The trail enters (or exits) each map only twice. The maps are saved and labeled in sequential order.

Elevation profiles and metrics for each section of the PCT and AT that is depicted on every map: PCT Elevation Profiles and AT Elevation Profiles

KML and KMZ are file formats developed by Keyhole (later acquired by Google) for mapping geographic data. These formats are open standards and widely used in trusted applications. As with any file, it's important to open them from reliable sources, but the formats themselves are safe and transparent.