We update the Appalachian Trail Pocket Profiles at least once a year. But, they are not all updated at the same time. The A.T. Guide contains town information (i.e. hours of operation, phone numbers, instructions, etc.) which has a tendency to change quite a bit and must be updated each January. However, the trail data (i.e. shelters, water sources, road crossings, etc.) for the Appalachian Trail changes so minutely that a hard dated annual update is not necessary for the pocket profiles. Minor changes can be covered in our errata pages. In many cases, the Pocket Profiles can actually be more up to date than the Guidebook since we update them throughout the year.