Rusk participated in a gathering of the mountain clans on Mount Rainier in 1905. Always a leader in the mountains, he went with a scouting party from Paradise Park around to the west side of Rainier, possibly up Kautz Cleaver, in an attempt to find a route that avoided the notorious rockfall on the normal Gibraltar route. Unsuccessful, the scouting party returned and rejoined the rest of the party for the ascent. Over 200 members from the Sierra Club, American Alpine Club, Mazamas, and the Appalachian Mountain Club were attempting the climb. Because there were so many attempting the climb, the clubs divided into two parties and climbed on succeeding days. Ninety-eight people completed the ascent including Rusk who volunteered as a leader of one of the groups.