[1] During and after the First World War, Mankin served as an ambulance driver and mechanic in the American Women's Hospital Unit No.

[1] After the war and earning her law degree, Mankin entered private practice as an attorney in Atlanta, Georgia.

[2] In 1946, Mankin was elected as a Democrat to represent the fifth congressional district of Georgia in the 79th United States Congress, filling the seat left vacant by the resignation of Robert Ramspeck.

Thanks to strong support from African-American voters, Mankin won by an 807-vote margin over conservative Tom Camp, Congressman Ramspeck's former executive secretary endorsed by the white supremacist and former governor, Eugene Talmadge.

Mankin was an unsuccessful candidate in that year's Democratic Party primary election when she sought renomination.