She studied at Clark Conservatory of Music (Chicago) and Bush Conservatory of Music (Chicago). At the age of eighteen she made her first appearance as a soloist with an orchestra, the occasion being a concert of the Detroit Symphony Orchestra, which was then under the leadership of Ossip Gabrilowitsch.
She performed with several opera companies, including the Vienna Opera Company (Chicago), Chicago Civic Opera Company, Ravinia Opera Company (Chicago) and in 1929, she made her debut with the New York Metropolitan Opera Company, where she was a participant for several decades.
Paramount Pictures starred her in five films, including "Rose of the Rancho" and "Romance in the Dark." She was honored with the degree of Doctor of Music, is the only woman to have sung for the entire assembled Congress of the United States, plus the Diplomatic Corps, Supreme Court and the President on the occasion of the 150th session of Congress.
While a young girl Swarthout suffered from a rheumatic fever, though it wasn't diagnosed as such until she was in her 50's. The disease left her with a damaged mitral valve. She died on July 7th, 1969 in Florence, Italy, at age of 68 due to her life long heart condition.