Physically unimpressive, Camp 4 was nevertheless a center of rock climbing development during the middle of the 20th century. Dozens of the most famous climbers in the world congregated at Camp 4 for years, learning from each other and trying out new ideas on Yosemite walls such as Half Dome and El Capitan. Some, such as Yvon Chouinard, made and sold climbing equipment in the camp's parking lot, laying the foundation for successful businesses later.