When World War II reached the Pacific, the Rivers moved to American Samoa where Mavis sang with her father for US servicemen.
Her career flourished after the family moved to Auckland. A clerical worker for the Farmers' Trading Company by day, she sang in clubs at night.
She made her first record in 1949 for the new Tanza label and later recorded for Zodiac in a variety of styles.
After a 12-month scholarship at a university in Utah, she returned to American Samoa and worked as a radio DJ.
Returning to the US in early 1955, she settled in Los Angeles, returned to office work and began playing with a Hawaiian quartet. Later that year she married the bass player.
After a short break to have two sons, she gained a following in Las Vegas and signed to Capitol Records in 1958, recording her first album with leading arranger Nelson Riddle.
She was nominated for the Grammy award for best new artist of 1959 but left Capitol after three albums and no hits.
"If you don't make trillions of dollars, you go," she told the Listener in 1990. "At the time Sinatra was thinking of forming a company, Reprise. This PR lady I knew said, 'Let's talk to Frank.' He said, 'Of course.' At the very beginning I was the only girl. There was Sammy [Davis Jr], Frank and me. I stayed with them until they merged with Warner in the late 1960s. Made a lot of singles."
Rivers dueted with Sinatra on a Christmas album and was a regular on the cabaret and casino circuit.
She returned to New Zealand to see her family and to sing, in 1981 appearing at a royal variety show for Queen Elizabeth II.
Rivers continued performing until her death, after a show in Los Angeles in May 1992. She remains a favourite with jazz purists internationally.
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