One of the early developers of the external frame for backpack, Lloyd F. Nelson got inspiration from his own experience hiking across Alaska to stake a land claim in 1920. The Trapper Nelson Pack Board replaced the rucksack, or "kidney buster" pack, with a wooden frame and canvas backboard that allowed a hiker to distribute the pack weight more comfortably over shoulders and hips and carry heavier loads with out the need to bend forward. A removeable canvas bag could be sized according to the volume of gear and supplies. After multiple prototypes and improvements, Nelson visited sporting goods and hardware stores in Seattle and Bremerton with a loaded pack to advertise. In time, the Trapper Nelson packboard was used to supply the Coast and Geodetic Survey, the Army Mapping Service, and was unofficially the preferred pack of the Boy Scouts of America.