On the cusp of 90, Ruth McMahon could still belt ’em out.

Last May, she finished second among 150 hopefuls in the Tri-Rail Senior Idol competition, capping a career that began with a Miami Beach hotel talent contest almost 60 years ago.

“She was absolutely marvelous,” recalled Tri-Rail public information officer Bonnie Arnold, a Senior Idol contest judge. “A true torchy, club singer . . . She sang That’s Life, which we all thought was so appropriate. She totally blew us away.”

Added Arnold: “I’ll bet she was something else in her heyday.”

Indeed she was. A stunning brunette who had been a Clairol hair model, she worked lounges and nightclubs during the 1950s, ’60 and ’70s in Miami Beach, New York, Las Vegas, Chicago and Boston.

McMahon spent a decade on cruise ships after her kids grew up, then with The Golden Girls of Music and Comedy: a gaggle of show-business veterans — singers, dancers and comediennes — who stayed busy on the South Florida condo and convention circuit, and into the ’90s, the Playmates Trio.

“Don’t tell them, but I would have done this all for nothing,” she used to tell her son, Joseph Crowley.

She sounded a lot like Patsy Cline, her son said. She could wail and growl and “take a ballad and make you cry.”

Happy in her personal life, she never succumbed to the show-business occupational hazards that troubled many of her contemporaries, her son said.

“She never became an alcoholic or smoker,” he said. “She used to say, ‘If I had a nickel for every drink a man bought me, I could retire.’ But she took one sip, then walked away.”

The twice-widowed McMahon, born Ruth McCarey on July 5, 1922, in Roxbury, Mass., died Dec. 20 at her home in Pembroke Pines.

She will be laid to rest Tuesday in the purple chiffon gown she wore for Senior Idol, her final public performance.

McMahon helped define

a generation of female performers who loudly and proudly proclaimed themselves “broads,” women like Martha Rae, Sophie Tucker, Belle Barth, Peppy Fields, Rusty Warren, Totie Fields, Patsy Abbott and Pearl Williams.

They had big hair, big voices and big personalities — usually with figures to match — and mixed song and patter in various shades of “blue,” from mildly risqué to down-and-dirty.

Crowley said his mother specialized in double entendre onstage, and limericks at home during the Nixon administration that still can’t be printed in a family newspaper.

“She was a trip,” her son said.

McMahon opened for Don Rickles, who once planted a big smooch on Joe Crowley’s face at a Vegas casino when he learned Crowley was McMahon’s son.

“One of the greatest compliments that was ever paid to her came from Billy Eckstine,” Crowley said. She opened for him, and the room loved her.

Eckstine “looked at the audience and said, ‘How about this Ruthie? I open my show on her applause,’ “ Crowley said.

She opened for Patti Page — and Connie Francis opened for her.

McMahon, whose father was a 1920s Boston vaudevillian, “grew up singing around the piano,” her son said. “She was very outgoing. The class clown.”