** Seeing all 50 states, the District of Columbia and the 5 permanently inhabited U.S. territories has been completed within a year's time by numerous travelers, but for most of us, it will be a lifetime endeavor. This set is only recommended for those travelers that anticipate achieving this goal within 5 years of purchase. The adhesive (stickiness) of an unused Travel Stamp can start to break down after 5 years. This situation only applies to Travel Stamps that haven't been used yet. Once you've used a Travel Stamp by applying it into your book, it will stick permanently.