Stephen was born in Denver and roamed the West with his geologist father. He worked as a park ranger in Colorado and Utah, earned a master's degree in ecology at the University of Arizona, served as director of the Museum of Northern Arizona Press, and for five years lived near Santa Fe, New Mexico. He has been a full-time free-lance writer and photographer since 1981.
As writer, editor, and photographer Trimble has published more than twenty books. His bedrock focus is the land; western wild lands and natural history.
Environmental historian James Aton has said that Trimble's "books comprise one of the most well-rounded, sustained, and profound visions of people and landscape that we have ever seen in the American West."
In 1996, Senator Russell Feingold (D-WI) read Trimble's essay from Testimony, "Our Gardens, Our Canyons," on the floor of the United States Senate during his plea to protect Utah wilderness. He concluded with, "That short piece of writing is so powerful…because it is a timeless statement about how people feel about natural places."
Trimble will spend the 2008-2009 academic year as a Wallace Stegner Fellow at the University of Utah's Tanner Humanities Center. Trimble makes his home in Salt Lake City and in the red rock country of Torrey, Utah, with his wife and two children. He has a stock photography business.