Sallie Hanna, leader in the Young Women's Christian Association, was born in Marquette, Michigan, on November 24, 1869, the daughter of Rev. Henry S. and Anna Hazzard (McCarer) Little. When she was two, the family moved to Denison, Texas, where her father served as superintendent of home missions for the Presbyterian Church in Texas. Her educational training included attendance in 1884–85 at Ferry Hall, a secondary school in Lake Forest, Illinois, and at Lindenwood College in St. Charles, Missouri, in 1886–87. She returned to Texas and married John M. Hanna, a Denison grocer, on October 18, 1888. In 1902 the couple, who had no children, moved to Dallas, where Hanna helped expand his family's wholesale grocery business. John Hanna died in 1926.
Sallie Hanna's involvement with the Young Women's Christian Association began in 1908, and by 1914 she chaired the religious-education programs for the Dallas YWCA and served on the association's national board. She subsequently did fieldwork to help increase the organization's service throughout the Southwest and was a member of a variety of national YWCA committees. In 1922 she was elected national vice president of the organization. Four years later she served two terms (1926–30) as national president of the YWCA, overseeing the activities of the association's 600,000 members in 4,000 centers around the country. She later served as a longtime board member, president (1933–36), and president emeritus of the Dallas YWCA.
Through her work with the YWCA she became involved with the Association of Southern Women for the Prevention of Lynching. During her national YWCA presidency, Hanna was a member of the Texas Interracial Commission and chaired the Texas ASWPL. She worked closely with ASWPL leader Jessie Daniel Ames, also a Texan, to obtain YWCA support for the association's programs, publicity, and educational campaigns. In 1934 she secured agreements from seven gubernatorial candidates to work to end lynching if elected.
Sallie Hanna shared the YWCA's goal to promote interdenominational cooperation among churches. She was an active member of the Presbyterian Church and a leader in the Texas Council of Church Women, the National Council of Federated Church Women, and the Federal Council of Churches. She was also a member of the Woman's Christian Temperance Union, the Dallas County League of Women Voters, the Dallas Council of Social Agencies, and the Dallas County Community Chest. In 1935 the Zonta Club of Dallas presented her its distinguished service award for her national and local leadership in the YWCA, her church work, and her interracial endeavors. She was named an honorary member of numerous organizations, including Beta Sigma Phi, a businesswomen's sorority, and Delta Kappa Gamma, a professional organization for women teachers. In 1950 the recreation building at the Dallas YWCA camp near Glen Rose was named in her honor. Sallie Hanna died in Dallas on November 8, 1957, and was buried in Fairview Cemetery, Denison.