The Forgotten Frontier is a 1931 American documentary film about the Frontier Nursing Service, nurses on horseback, who traveled the back roads of the Appalachian Mountains of eastern Kentucky. It was directed by Mary Marvin Breckinridge, and featured her cousin, Mary Breckinridge, who was a nurse-midwife and founded the Frontier Nursing Service. Also featured are the people of Leslie County, Kentucky, many of whom reenacted their stories.