US-based portal offering FAQ, links, forums, and a members-only section where clues can be submitted.

Introduction, contact details, and guidelines for letterboxing in the Dartmoor area.

Introduction, tips and things to avoid, news, survey, and letterbox clues for the Dartmoor area.

Article describing the basics and the factors that motivate people to start letterboxing.

Discussion group for US letterboxers.

Article by Caroline Kettlewell describes her discovery of the activity.

Rubber stamp carver Mitch offers instructions on how to carve a stamp, and some examples.

Family and friends offer clues to letterboxes in New Jersey and Pennsylvania.

Brief article includes details on supplies and features instructions for participation with children.

Clues to quick and easy letterboxes to find while traveling on Route I-95, from Maine to Florida.