Some musical discoveries function like a subway station: They become hubs for vibrant lines connecting clubs, lofts, and basement studios. Others are like stalls in a bustling marketplace, or a popped trunk in a parking lot, promising the best of the block.

But there is a type of music that’s a dead end. You can’t easily connect it to a scene or a label. It’s not some treasure to be imparted—you hand it to someone like a furtive cigarette. There’s no romance, no mystery other than how it got recorded. It may be unclear who the music was ever for, but it’s against seemingly everything: lyricism, artistic remove, conventional rhythmic sense. For most people, that kind of art prompts a quick jab at the stop button and dark thoughts about delusion or mental illness. For a select few, it represents the last frontier of musical expression.

For decades, author, producer, and archivist Irwin Chusid has been patrolling that frontier with X-ray spex and a ray gun. A self-described “connoisseur of marginalia,” Chusid has been a DJ on New Jersey’s legendary freeform radio station WFMU since 1975. In the early ’90s, he was scraping by on freelance writing and producing albums: at one point, his parents were loaning him $50 a month so he could eat. His fortunes shifted when Bar/None Records asked him for a reissue pitch, and he suggested the experimental big-band producer Juan Garcia Esquivel. 1994’s Space-Age Bachelor Pad Music—like the Stereolab EP from the year prior, named after a phrase coined by animator and exotica collector Byron Werner in the 1970s—sold a shocking 70,000 copies, helping move the lounge revival mainstream.

Chusid’s other work during the decade (reissues of forgotten bandleader and electronic-music pioneer Raymond Scott, liner notes for Rhino’s Golden Throats series of singing celebrities, producing R. Stevie Moore) showed someone able to make a meal out of bygone (or bad) tastes. But it was a little-noticed reissue of a laughably obscure 1969 album that changed Chusid’s destiny: Into Outer Space with Lucia Pamela. Chusid first heard Into Outer Space in 1984, when a WFMU listener mailed him a homemade tape. It took him four years to obtain an original copy, and another three before he got it released on Boston’s Arf! Arf! label.

Lucia Pamela was a bon vivant and lifelong entertainer. In 1926, she was named Miss St. Louis; in the ’30s and ’40s, she led the all-women big band Lucia Pamela and the Musical Pirates. After the group disbanded, she reportedly played accordion for Lionel Hampton and Paul Whiteman; she also performed at USO shows with her daughter Georgia, billed as the Pamela Sisters. When Lucia was 65, she recorded her only album, a zany, jazzy romp that she would insist was recorded on the moon. According to legend, she played every instrument, but it’s also possible she kidnapped a Dixieland combo at gunpoint. The prevailing spirit is that of a public-access kids’ show running on fumes and flopsweat; her voice is all brass and zero polish. In college, I found that the 90-second closing track “In the Year 2,000!” was the perfect way to pad a mix CD’s runtime. “We’ll even play football too, on the year 2000!” she hollers. (In January 2000, as it happens, the St. Louis Rams won their first Super Bowl. The team’s owner was Georgia Frontiere, Lucia Pamela’s daughter.)

The Into Outer Space reissue didn’t move the needle, but the project had a deep effect on Chusid. For several years, he had hosted a radio show called Atrocious Music. It was filled with audacious camp: Golden Throats-type performances, school bands, Bible-thumping records, and the occasional bizarro record like Into Outer Space. But after meeting Lucia Pamela—by then in her late 80s, living in a bungalow outside the Rams’ offices—Chusid changed the show’s name to Incorrect Music. “I just began to realize that I need to respect these people a bit more,” he told Perfect Sound Forever in 2007. “And deal with them on their own terms, rather than dealing with them as a zookeeper.” A few years later, when a publisher asked Chusid for a book pitch, exotica didn’t come to mind. But Lucia Pamela did.

Released at the decadent height of the CD Age, when pop’s biggest stars were routinely moving a million albums a week, Songs in the Key of Z (simultaneously released as a book and album) was the first major attempt to define and survey “outsider music.” The album presents 20 songs from the late ’60s to the mid-’90s, all recorded by artists on the musical fringe. Some of them were artists Chusid had first shared on WFMU; others were thrift-store finds or esoterica passed around record-collector circles. In a departure from the way outsider music was generally conceived, several cuts were pulled from so-called “vanity” records: limited-run, self-released albums that were previously only of interest to hardcore cratediggers.

Previously, most compilations of out-there songs (like Arf! Arf!’s Only in America, or the two-volume Incredibly Strange Music set issued by V. Vale and Andrea Juno’s venerable RE/Search zine) fixated on cash-out novelties: sitar covers of pop hits, teensploitation documentaries, lounge atrocities. The ones that dug deeper were narrower in focus. The four-volume MSR Madness series from indie-comics publisher Carnage Press was solely devoted to song-poems, a mail-order hustle that converted amateur lyrics into recordings banged out by beleaguered studio rats. Arf! Arf!’s 1996 release, The Talent Show, documented a Boston church’s amateur night in 1981, featuring performances from youth-group kids and residents of nearby nursing homes.

One of those residents was Jack Mudurian, who could breathlessly toggle between dozens of pre-WW2 pop songs. Arf! Arf! issued another of his extemporaneous medleys—clocking in at an astounding 129 songs in 47 minutes—as Downloading the Repertoire, which Chusid excerpted for Songs in the Key of Z. Mudurian—who only performed for friends, bygone ditties spilling from his clogged pipes—is the outlier on an album full of them. “Outsider music is difficult to catalog,” Chusid admitted in his book’s introduction. “It’s fragmented and lacking in common structural threads.” He suggested a few throughlines: artists who avoid convention instead of obeying or challenging it, a lack of commercial or critical validation, and a compulsion to create.

The closest Chusid came to a platonic ideal was in the Lucia Pamela chapter, where he noted his preference for “exotic, offbeat, calamitous, and visionary recordings—provided the artist was sincere.” His intentionally wide net caught song-poets and Living ECK Masters, Liberian legislators, and Swedish Elvis impersonators. The artists on Songs in the Key of Z released their music on private pressings and major labels. Some were championed by iconic insiders, others were ridiculed on countless radio shows. (In Tiny Tim’s case, both.) Because outsider music was a foreign concept outside of hardcore record collectors and kitsch obsessives, Chusid tended to select artists with fascinating biographies. Other choices, like Harry Partch and Captain Beefheart, were selected for their “marquee value,” which should tell you something about the level of obscurity involved. Chusid was never a fan of Jandek, but the Texan avant-blues recluse was the underground’s most notorious mystery: On went “They Told Me I Was a Fool,” a no-fi acoustic-glam kiss-off from his 1978 debut album.

Other than perhaps Jandek, the artists on Songs in the Key of Z have nothing in common with the banjo-toting tricksters and spectral messengers of Greil Marcus’ Old, Weird America. They’re more like Casper the Friendly Ghost: cheerful, underappreciated, and prone to powering through walls without a second thought. Peter Grudzien had been an out gay country musician since the ’60s—in theory, prime outsider material. But he’d already been drafted by the private-press collectors, who viewed his 1974 self-produced album, The Unicorn, as prime “real people” music. The Unicorn was psychedelic yet plain-spoken, religious and randy: a horny elegy for a strain of country that never got to flourish. The album was reissued in 1995 with six new recordings; Chusid selected Grudzien’s cover of “There’s a Star-Spangled Banner Waving Somewhere,” a WWII-era cannon-fodder classic. Grudzien gives the lyric a queer update (“I’d see queens and dykes and fairies who would serve there”) while inexplicably yearning to fight terrorists. Imagine a gay reactionary Folkways LP with a malfunctioning metronome: Now that’s outsider music.

There was no need to share credit for William “Shooby” Taylor, the Human Horn, whose recordings were hand-delivered to WFMU by their incredulous engineer. Taylor was a retired postal worker an aspiring jazz vocalist from Brooklyn. He’s represented here by “Stout-Hearted Men,” a number from The New Moon, a 1920s American operetta set during the French Revolution. The text revels in the power of fraternité—an irony, as Taylor spent decades trying to connect with anyone. Jazz musicians cold-shouldered him out of the clubs; when he appeared on Amateur Night at the Apollo, he was booed off the stage within seconds. “I was hurt, very hurt,” he recalled in a 2002 WFMU interview. “I figured, oh, I did it wrong… After months and months of thinking about it, I said I did it the way how I wanted to do it!”

How did he want to do it? Playing a phantom saxophone while scatting in a grammar of his own design. Though perfectly capable of dextrous vocal runs, Taylor preferred a steady diet of open vowels, honking out shraws and splaws with abandon. On Key of Z he’s accompanied by a chirpy Farfisa, though he liked to dub himself onto other musicians’ recordings, even over other vocalists. That practice made a legal Shooby Taylor retrospective extremely difficult: licensing issues delayed the project until 2017.

The odd Who’s in There or “Hoogie-Boogie Land” aside, outsider music is for auteurs. To collaborate is to attenuate your vision; if your collaborators somehow share your wavelength, then you’re in danger of creating a scene. Captain Beefheart—an intuitive but unschooled musician who often had to draw, gesture, or whistle to his Magic Band—makes Chusid’s cut. So do the miraculous Shaggs, who he correctly calls the “godmothers of outsider music.”

The Shaggs were Betty, Dot, and Helen Wiggin: three teenage sisters from a small town in Southeast New Hampshire. In 1967, for no discernable reason, their father decided that they needed to be a rock’n’roll act. Austin Wiggin pulled the girls from school, enrolling them in a musical boot camp of his own design: hours of exercising and rehearsals, a Saturday-night residency at the town hall. In 1969, the Wiggins recorded an LP, Philosophy of the World. According to legend, Austin—who called himself the band’s “proprietor”—was anxious to “get them while they’re hot”.

Philosophy of the World was a generation’s introduction to the concept of outsider music. Chusid first encountered it in the late ’70s, on R. Stevie Moore’s recommendation. “We acknowledged the playing was ‘bad,’ but there was also something extraordinary about it,” Chusid remembered years later. “It had a purity and guilelessness that transcended mere incompetence.” Around that time, NRBQ’s Terry Adams stumbled across a copy of the album and flipped out. He worked with the Shaggs on a 1980 reissue for his Red Rooster label; the promo material compared Dot to hipster favorites like Harry Partsch and Sun Ra. In his rave writeup for the Village Voice, Lester Bangs tossed in free-jazz saxophonist Marzette Watts. As the headline implies—“Better Than the Beatles (and DNA, Too)”—he wasn’t above using the Shaggs as a cudgel. His appreciation teetered between irony and sincerity, setting the tone for all outsider-music enthusiasts to follow: “How do they sound? Perfect! They can’t play a lick!”

There were outsider musicians before the Shaggs, of course. Some of them were much easier to find, because they were on television. They didn’t necessarily strike listeners as revolutionary: DIY salvos against midcentury monoculture or whatever. In fact, they were considered comedy acts. Elva Miller was a contentedly nonprofessional singer in Claremont, California: her retiree husband booked her sessions at a local studio, and whatever songs she pressed up she tended to give away. In the mid-1960s, some of these recordings fluttered into industry hands. Miller signed to Capital, which paired her hyperwarbled, go-for-broken vocal stylings with current pop hits. The singer resented the process—she accused her producers of recording when she was tired, cutting songs before she got a handle on them, and issuing the worst takes—but for a couple of years, she was a fixture on late-night TV, and her albums reportedly sold in the hundreds of thousands.

Mrs. Miller’s unlikely success put her in the lineage of the infamously detuned diva Florence Foster Jenkins and the vaudeville-era act Cherry Sisters, whose moralistic performances were panned, heckled, and usually standing-room only. The latter two acts get entries in Chusid’s book, as does Tiny Tim, who was even more famous—and much less conflicted about that fame—than Mrs. Miller. Born Herbert Khaury in 1932, he grew up obsessed with the moony crooners of bygone days. Like Jack Mudurian, Khaury had a massive store of 78s spinning in his head. But he wanted to share them with everyone. After a few years plying his act around Greenwich Village and stealing the occasional movie scene, Tiny Tim performed a brief medley—pulling his ukulele out of a shopping bag—on the 1968 debut episode of Rowan & Martin’s Laugh-In.

He was an immediate sensation, as much for his fey manner and nearly androgynous look as for his unearthly falsetto. He was infamous for spelling out any word relating to sex, but cheerfully told one interviewer that “a woman in her prime is between the ages of twelve and eighteen.” He married the 17-year-old Victoria Budinger on The Tonight Show; 40 million people tuned in.

But unlike with Mrs. Miller, people didn’t wonder whether Tiny Tim was in on the joke. They wondered whether there was a joke at all. In May of that year, Newsweek ran a Tiny Tim profile titled “The Last Innocent”. Two months later, Rolling Stone put him on the cover, with writer Jerry Hopkins describing the artist as “quite odd, but above all, gentle and beautiful.”

Odd, gentle, and beautiful: You can hear the combination in the public-access pop of B.J. Snowden’s “In Canada”. The lyrics read like a mayoral proclamation written on a lunch break (“You see the ice rink glow/To the waterpark, kids can go”), but Snowden, Berklee class of ’73, adds intrigue by keeping to a minor key. Her voice is free of vibrato but full of drama, the way she sings “in Saskatchewan!” like a third-act reveal has stuck with me for a quarter-century.

It may seem odd to look for a holy dimension in outsider music. Even the explicitly spiritual tunes move in mysterious ways. On “At the Grass Roots,” Sri Darwin Gross, 972nd Living ECK Master, burbles the charms of his Eckankar movement over a full Disney orchestra, cartoon bunnies and all. The uncredited “Virgin Child of the Universe” is the only song-poem on Key of Z, and it’s a doozy: a cosmosexual nightmare of release, ritual, and pursuit. Its producers, blessedly, decided to track it as a Stax-style country-soul ballad.

In the visual arts, though, outsider art has long been idealized. In 1911, the modernist collective Der Blaue Reiter held an exhibition in Berlin. Like many artists of the time, they believed that the new century would become a “great spiritual epoch,” one that all art traditions were anticipating in their own way. Their exhibition placed “primitive” and folk art alongside contemporary abstract and expressionist paintings. A supplemental almanac (like Chusid, they also issued a book) reprinted over a dozen works from children. “The most important thing is not whether the form is personal, national, or has style, whether or not it is related to many or few other forms,” wrote the Russian painter Wassily Kandinsky. “The most important thing in the question of form is whether or not the form has grown out of inner necessity.”

In 1922, a 36-year-old German psychiatrist named Hans Prinzhorn published Bildnerei der Geisteskranken (Artistry of the Mentally Ill). The book profiled the work of 10 artists with schizophrenia, each in psychiatric care. It went off like fireworks in the heads of Western modernists. In Prinzhorn’s subjects, they saw inner necessity: artists creating without a thought about the academy or the marketplace, effortlessly drawing from their subconscious, painting not as a profession but as an impulse. It wasn’t their form that insider artists tended to imitate. It was their drive, their speed.

So it’s a little funny to think about Daniel Johnston and Wesley Willis. As visual artists, their portfolios were prototypically outsider: Johnston’s cartoon cosmology of spiritual combatants, Willis’ beautifully hatched and gently geometric renderings of cityscapes. As musicians, they were just as distinctive: Johnston poured wry pop songs into a cheap boombox, Willis talked about bands he saw and demons he battled over preset keyboard arrangements, always tagged with a commercial slogan. But they were also hustlers. Each man built his reputation on a stream of self-released, self-illustrated albums. Each got a prominent underground co-sign: Jello Biafra released his favorite Willis tracks as a best-of on his Alternative Tentacles label; Kurt Cobain wore a Daniel Johnston “Hi, How Are You” shirt pretty much everywhere in 1992. And each parlayed their buzz into a (brief, incredible) major-label deal.

Contrary to the concept of outsider musicians as oblivious naifs, Johnston and Willis were frequently self-aware, brutally honest, and intentionally funny. Chusid quotes plenty of friends, caretakers, and collaborators saying as much. And yet, his writing keeps drifting into the language of the sideshow barker: “huggably pudgy… and disarmingly gnomelike,“ “oxlike brainpower,” “electroshock poster-boy,” “not the most appetizing of human specimens.” This, too, may be Chusid trying to meet skeptics halfway. It was an age of the marginalized becoming a mass-market spectacle: COPS was in the middle of its network run; Jerry Springer’s tabloid talk show was battling its way to the top of the Nielsen ratings. There’s a world in which Wesley Willis wasn’t a guest on Howard Stern, but a member of his Wack Pack.

At the bottom of Key of Z’s back cover are some closing commands: “Get off the focus-group treadmill. Celebrate true diversity. Go OUTSIDE for some fresh sounds.” It’s a Gen-X way of saying touch grass: “outside” as a place for exploration, not exile; for play instead of pain. It’s no wonder that Chusid preferred the sunnier pastures of Shooby Taylor and B.J. Snowden to Jandek’s self-dug oubliette.

And so did the listening public. The year Key of Z was released, a record collector named Brian Linds bought a 23-year-old album from a British Columbia thrift store. It was a collection of pop songs performed—with extraordinary gusto—by Vancouver-area elementary schoolers. Linds alerted Chusid, who tracked down the kids’ music teacher and unearthed additional recordings. Just like with Esquivel a decade prior, Bar/None agreed to release the set. Released in 2001, the Langley Schools Music Project’s Innocence and Despair was a left-field hit, hailed by everyone from David Bowie to Mike White, whose School of Rock script was in part inspired by the Langley kids. Meanwhile, the stories on Key of Z continued to resonate. In the years after the album’s release, nearly half its roster was featured in documentaries. Chusid oversaw three more Key of Z volumes, none of which included Jandek.

Twenty years ago this month, I was sitting in a Masonic theater, watching Jandek’s first American show. I’d never even considered that he would play live—I had fully bought into the idea that Jandek was a musician who could only exist in mystery. But there he was, playing capably off a bassist and two drummers recruited specifically for that night. He was no longer someone who had to make music. He was someone who wanted to, and wanted others to witness its creation. I sat there in a daze with a couple hundred other people, all of us invited inside.