Who is Saslly Cochran Rausch from --and Ladies of the Club and what is their importance?

Sally Cochran Rausch is good friends with Sally and Anne. The girls are initially invited to become members of the club by Mrs. Lowrey on the day they graduate from high school. Over the course of the novel, Sally marries Ludwig Rausch, who dreams of starting a rope factory in Waynesboro. Sally is described as headstrong and uncompromising. A proud woman, Sally never lets any but her closest friends know that she suffers from debilitating and painful arthritis, preferring that people believe she's simply gotten fat and lazy.