Mark led the design process for the Arizona National Scenic Trail from the Coronado National Forest boundary north to Saguaro National Park. He also assisted Saguaro National Park staff in laying out the Quilter Trail connection from Hope Camp. Mark organized and led volunteer projects in the construction of 35 miles of the trail between the Coronado National Forest and Saguaro National Park – a project that took seven years and required more than 100,000 hours of volunteer labor.