The Adventures of Superman bowed on radio in 1940, initially as a syndicated series based out of WOR radio in New York before being picked up for national syndication by Mutual.
What most of you don't know is that some of the familiar supporting cast, such as Jimmy Olsen and Daily Planet editor Perry White, and certain elements of Superman lore, such as Kryptonite, originated on the radio show, which ran for 11 years here in the US, while a separate series aired in Australia. The series began as a 15 minute show airing 3-5 times a week, then expanding to a full half hour, three times a week, beginning in 1949.
Bud Collyer, who'd voiced the Man of Steel in 17 animated shorts produced by Paramount & Famous Studios, essayed the part here, joined by Joan Alexander as Lois Lane. Narrator Jackson Beck was the 2nd man to fulfill those duties, and would also handle the role of Alfred, Batman's faithful butler, when the Caped Crusader made guest appearances, and Beany, a copy boy at the Planet. Beck would later reprise as Beany and the narrator, in addition to Perry White & Lex Luthor, in the 1966-70 Filmation animated series. Another Filmation cast member, Jack Grimes, was the 2nd radio Jimmy Olsen, but is better known to animation fans as the voice of Speed Racer, another 60's icon.
Collyer left the show in 1950 to move to television (Beat The Clock), with Michael Fitzmaurice in the unenviable role of succeeding Collyer as Superman/Clark Kent. If there was a jump the shark moment in the series, that was it. Collyer would return to the role for the Filmation series in 1966.
Right now, here's "The Silver Clipper", part 6 of a 10-part story arc, courtesy of Internet Archive.
You'll forgive the skips. Apparently, it was a faulty copy.
A little too much expository dialogue for my tastes. Your actual mileage may vary.