November 1955 (age 56)

Sigurd begins working on the manuscript that ultimately will be published in 1961 as The Lonely Land.

November 1970 (age 71)

Sigurd and two other conservationists complete a management plan for Yellowstone and Grand Teton National Parks that is quite critical ofthe National Park Service, saying we need to get away from the oversimplification of phrase "parks are for people." They want a daily ceiling on visitation that caps it at the current amount of 9,000 vehicles per day; they want parking areas outside the parks with buses encouraged; study of monorail or other mass transit; regional planning with all agencies; no more boat sewage disposal in Yellowstone Lake; and they agree with the famous Starker Leopold report of the 1960s that it is important to allow natural processes such as fire, and to eliminate the garbage dump conditions that make grizzly bears too conditioned to humans.