- LETTERBOXING NORTH AMERICA 2524 clues online in 50 states and 7 countries Last tally: 22-Jul-2002 Getting Started | FAQ's | CLUES | Submit Clues | Talk List | Regalia | KIDS | What's New LETTERBOXING is an intriguing pastime combining navigational skills and rubber stamp artistry in a charming treasure hunt style outdoor quest. A wide variety of adventures can be found to suit all ages and ...www.letterboxing.org