Rodessa Barrett Porter, the last living member of the Barrett Sisters, a Chicago gospel trio renowned for their exuberant operatic sound and thrilling harmonies, died on Dec. 16 in Harvey, Ill. She was 94.

Her grandson Jonathan Scrutchens said her death, in a hospital, was from complications following a stroke.

The Barrett Sisters were an electrifying act, anchored by Delois Barrett Campbell’s extraordinary range. She sang most of the leads, but Ms. Porter, the youngest, and Billie Barrett GreenBey, the middle sister, were potent soloists, too.

The three of them had grown up listening to the Andrews Sisters on the radio and modeled themselves after them. There is nothing, they often said, quite like sisters harmonizing.

If the mission of gospel music is evangelism, the Barrett Sisters surely must have been responsible for more than a few converts. Their smiles were beatific. They were known locally to many as the Sweet Sisters of Zion.