And Kiefer continued to improve, reaching his peak about a decade later, when he was in his 20s. In an NPR program about Kiefer in 2008, the sportswriter Frank DeFord said that if the war had not interrupted his career, “he’d be to the backstroke what Pablo Casals was to the cello.”

Tall and good-looking, Kiefer was courted by Hollywood and drew comparisons to matinee idols. “He is a Van Johnson in pastel drawers, the greatest backstroke swimmer who ever lived,” the sports columnist Red Smith wrote.

Kiefer went into business instead, and thrived.

Sonny Boy Kiefer, as he was widely known, broke his first world record at the age of 15, and for 15 years he held every world backstroke mark. He was the first man to swim the 100-yard backstroke in less than one minute, according to the International Swimming Hall of Fame, which inducted him in 1965.

He also set world records in the individual medley, and from 1935 through 1945, when he retired from swimming, he won 58 national championships in backstroke, individual medley and freestyle. From 1934 through 1943, he won more than 200 consecutive backstroke races.