Mary Johanna Harum was born in Madison, South Dakota and lived in Sioux Falls, South Dakota, as well as in Denmark, as a child and teenager. She speaks both Danish and Swedish fluently. Hart, who competed as Mary Harum when she was Miss South Dakota 1970, was a semi-finalist in the Miss America 1971 pageant. In 1968, Hart graduated, first from Augustana Academy and in 1972 from Augustana College in Sioux Falls. While teaching English at Washington High School for two years, she also produced and anchored her own talk show on KSFY-TV, the local NBC affiliate.