One Square Inch of Silence is a noise-control project in the Hoh Rainforest of Olympic National Park, created in 2005 by author and sound-recording specialist Gordon Hempton. Marked by a small red stone, it came to symbolize the protection of natural quiet in a place regarded as the quietest in the United States. The project helped make silence a public cause worth defending. Pilot Philip Greenspun said some airlines voluntarily rerouted flights to lessen noise over the area. Hempton also founded an organization to fight jet noise in Olympic National Park and other parks, and the effort appeared in the 2010 documentary Soundtracker.