It all started in England a long time ago, when a gentleman left his calling card in a bottle tucked into a bank at Cranmere Pool in Dartmoor. It's been a popular sport there for ages, but began in the United States in 1998 after an article appeared in Smithsonian Magazine. Letterboxing started off slowly here, but has recently grown rapidly after many more articles appeared in newspapers and national magazines.

Read the Smithsonian article.