Peggy Lee’s 1972 album “Norma Deloris Egstrom from Jamestown, North Dakota,” which was just reissued in a deluxe, expanded edition, is notable at first as a confluence of those round numbers that so many seem to love: It’s the 50th anniversary of the recording, which coincidentally was her 40th original, full-length album project. It would also be, unfortunately, her last album with Capitol Records.

I am now embarrassed to admit that I never paid much attention to most of Lee’s work from this period, other than her rather arresting hit of 1969, “Is That All There Is.” It’s not that she could no longer sing, but it’s what she chose to sing that was the problem. Rather than the jazz, blues, and songbook standards that she sang better than anybody, her recordings of the late 1960s and early ’70s found her chasing the pop market in a way that seemed embarrassing to long-time fans.  

The 1969 album “A Natural Woman” pivots around a poor choice for a “cover,” in multiple senses of the word. The Carole King / Aretha Franklin hit is not a particularly good song for her; worse, the front of the LP jacket shows Miss Lee posing in a field of tall grass. She’s stunningly beautiful as always, but looks as if she had just spent the previous six hours getting lacquered in a beauty salon, precisely the opposite of any reasonable definition of natural.

In listening to “Norma Deloris Egstrom” now — hopefully with fresh, unbiased ears, and knowing that it represents a turning point in her career — it now more obviously belongs in another category altogether. In perspective, the album is part of a continuum with Frank Sinatra’s “September of My Years” (1965) and Tony Bennett’s “Astoria: Portrait of the Artist” (1989). In all three, remarkable artists take a selection of songs written by other people and transform them into highly intimate and individual statements, autobiographical reflections on life, love, youth, and maturity.

The album is much deeper and more personal than many of us had previously realized. This makes it all the more surprising that it largely wasn’t her idea, as we learn from the highly detailed annotation by the foremost Peggy Lee scholar and discographer, Ivan Santiago. For most of her classic albums of the ’50s and ’60s — as I know from my own conversations with her musicians as well as the lady herself — Lee, like Sinatra, was the central creative force both in front of and behind the microphone, picking all the songs as well as dictating the general shape of the arrangements.  

According to the collective testimony of those involved, though, “Norma” was conceived when Brian Panella, then Lee’s manager, introduced her to Tom Catalano, a pop-oriented producer then as now best known for his long collaboration with Neil Diamond. Mr. Catalano picked out the songs with Lee, and appointed the 29-year-old arranger Artie Butler, a lifelong Peggy Lee fan, as musical director.  

Mr. Catalano, according to testimony in the notes here, wanted to title the album “Super Bitch” — the b-word was then becoming trendy in jazz and pop — but she wouldn’t go along with it. It was her daughter, Nikki, who came up with the final title, a reference to Lee’s original pre-showbiz name and the town where she had been born. 

Yet even though Lee had less input than usual, the album evolved into more of a personal statement than any of her other works from this period. Lee takes songs that seem several generations away from her comfort zone and turns them into a deeply interior “journey,” to employ a 21st century buzzword.   

Leon Russell’s “A Song for You” is a revelation here; in the dramatic set-up of the text, Lee is standing on a stage performing, but she’s addressing the words to one specific person, even while, at the same time, she’s plumbing the depths of her own psyche, taking a deep, considered look at both her professional and private selves.  

Mr. Baker’s arrangement is a marvel, heightened by the sound of a metronome — through the percussion instrument known as “tempo blocks.” The effect reminds us that time is ever present, both in a musical sense, as in the time signature, and in terms of the passing of the years.  The singer is not only getting older — at that point 52 was relatively long-in-the-tooth for a pop star, which is an issue in itself — but world culture and music are constantly changing around her. “A Song for You” becomes a deep self-exploration, one that extends outward as well as inward.

In the LP days, it seemed more obvious that the A side was all contemporary songs, whereas three of the five numbers on Side B were older standards. This perhaps symbolizes a voyage backward from the present. Lee claimed to have learned “Just for a Thrill” from Ray Charles, but I wouldn’t be surprised to discover that she’d heard composer Lil Hardin Armstrong play it in early 1940s Chicago. This version, enhanced by Mr. Butler’s own lightly bluesy piano accompaniment, is even more arresting than her 1961 performance of the song on her “Basin Street East” album.  

The original album was only 32 minutes, but the new edition, diligently produced by Lee’s granddaughter, Holly Foster Wells, is considerably enhanced by bonus material.  “Pieces of Dreams,” arranged and conducted by the composer, Michel Legrand, is an obviously perfect song for Miss Peggy Lee, and she does not disappoint. 

“It Changes,” however, is a brilliant outlier. Written by maestro brothers Richard and Robert Sherman for Charlie Brown — yes, the Peanuts comic strip character — to sing in the 1972 animated film “Snoopy, Come Home,” Lee renders it as a soul-searching soliloquy. There are also several worthwhile alternate takes.

After having made one of the best albums of her career, Lee felt that Capitol Records completely dropped the ball on the release, and as a result she was not upset when her contract wasn’t renewed. It should have been a beginning — one wishes she’d gone on to make more such albums with Mr. Butler and Mr. Catalano — but instead it was the end of an era. Which makes the conclusion of the actual LP so profound. 

It closes with two standard ballads of World War II, the period when Lee first became prominent, “The More I See You” and “I’ll Be Seeing You.” 

Mr. Catalano says that he had been thinking of Lee’s late first husband, Dave Barbour, when he suggested Leon Russell’s “Superstar” to her. It doesn’t seem like much of a stretch to imagine that she was also thinking of him when performing these two songs, which flow into each other seamlessly, like a medley.  

Yet considering where she was in her life at this moment, I would bet that she was also remembering a moment and even an entire era that was no more — reliving her youth and, at the same time, saying goodbye to it.