One of the most important innovations of the 1990s to the canon of psychedelic folk-rock was "slo-core", variously defined depending on local variations, but basically a slow, dreamy, melancholy version of dream-pop, a direct descendant of Galaxie 500 and Yo La Tengo, that typically required lengthy and restrained compositions.

Slo-core was sanctified in Chicago by Codeine (11) with Frigid Stars (1991). John Engle's guitar distortion was so dilated to sound like an organ, Chris Brokaw's drumming sounded like bells tolling for a funeral and Stephen Immerwahr's sleepwalking litanies evoked Nick Drake and Tim Buckley. That emotional "black hole" attained nirvana on White Birch (1994), featuring new drummer Doug Scharin: longer songs, deeper trance, slower tempos, as if they were aiming for a song with no title in which the group does not play and does not sing.

North Carolina's Seam (12), the project of former Bitch Magnet's vocalist Sooyoung Park, fashioned the floating timbres and shimmering textures of Headsparks (1991) but, more importantly, the unstable filigree of The Problem With Me (1993), a sedate but also forceful work that seemed to merge tender folk-pop and neurotic hardcore, and felt like the slow-motion replay of a volcano's eruption. Are You Driving Me Crazy? (1995) was both an even more personal show of the leader and a less abstract, almost "poppier" affair, which led to the atmospheric melodies of The Pace Is Glacial (1998).

San Francisco's Red House Painters (111), an acoustic quartet led by introverted poet Mark Kozelek, penned the depressed mantras of Down Colorful Hill (1992): shy guitars that played chords as if they were reciting rosaries, and moribund dirges that seemed to end before beginning but then lasted for eternity, created quietly unnerving atmospheres that blurred the border between sorrow and ecstasy. Like with the music of Leonard Cohen, Tim Buckley and Nick Drake, the effect was both subdued and majestic, a contradiction that became the quintessence of their art. The demo-quality of those recordings contributed to the sense of philosophical melancholy, but Red House Painters (1993), also known as Rollercoaster, revealed a much lighter and brighter mood: rather than whining, Kozelek was contemplating the universe. Each song was a moment in time, an impressionistic watercolor. Ocean Beach (1995) brought even more life to the compositions, dispensing with the most austere elements of their slow acoustic chamber folk. Mark Kozelek's next project, Sun Kil Moon, interpreted Kozelek's existential spleen in the 14-minute cryptic tour de force Duk Koo Kim, off Ghosts Of The Great Highway (2003), and especially in the sprawling streams of consciousness of April (2008).

Minneapolis' trio Low (15), too, resurrected the depressed and anemic mood of Nick Drake, but then wed it to LaMonte Young's minimalism and to the Cowboy Junkies' lounge melodies. I Could Live In Hope (1994) was the quintessential case of "the whole is more than the sum of its parts": the parts were trivial and scant, but the whole was a triumph of unbridled creativity. Ascetic more than mournful, it sounded like the rock equivalent of Japanese haiku and Tibetan tangka, an art of frigid ballads that drowned in a lattice of empty notes. Low's "song" was chamber music for emotions that slowly faded away, that were never truly felt. At the same time, the unbearable delay and dilation of musical structures fostered and maintained an intensity of feeling that an ordinary refrain would have released in a few seconds. The tranquil jams of Long Division (1995) were as musical as circles spreading in a pond, but were given a soul by the whispered thoughts of guitarist Alan Sparhawk and drummer Mimi Parker. The Curtain Hits The Cast (1996) turned to electronic keyboards in order to relieve the gloom and lighten up the ambience, and Secret Name (1999) expanded the instrumentation by adding a string section, piano and timpani. Low regressed to a more conventional format for Things We Lost In The Fire (2001) and attained formal perfection with Trust (2002), a masterpiece of subtle metamorphoses, glacial counterpoint and ghostly religious music.

Texas' Bedhead (2), led by Matt Kadane, exlored a state of mind between psychedelic trance and teenage angst on What Fun Life Was (1994) and Beheaded (1996). Their ameobic pieces "grew" rather than simply exist: they were the object of a gradual, evolutionary (and potentially never-ending) process that slowly brought the emotions into focus.

The "slo-core" style became ubiquitous, gathering momentum around the country.

Ethereal pop, 1990-95

A variant on "male" slo-core was a style of fragile folk-pop ballads for female whispers and understated arrangements, more or less inspired by the Cowboy Junkies.

The concept was pioneered by a group that originated from the psychedelic movement, Mazzy Star (2). Rain Parade's and Opal's guitarist David Roback replaced Kendra Smith with a more delicate vocalist, Hope Sandoval, and greatly expanded the scope of his music on She Hangs Brightly (1990), a melting pot of acoustic folk, Delta blues, oneiric acid-rock and laconic lounge jazz. So Tonight That I Might See (1993) barely increased the melodic element of their tender lullabies, which reached alternatively for the galactic, subliminal, mystical and impressionistic levels.

Somewhat related to this atmospheric and psychological school were the electronic vignettes of His Name Is Alive (3), the brainchild of Michigan's multi-instrumentalist Warren Defever who employed different female singers for each album. Rhythm was optional on Livonia (1990), an experimental work that indulged in tape loops and samples but mostly relied on an elegant combination of ghostly neoclassical vocals and surreal electronic effects. Guitars were given more prominence on Mouth By Mouth (1993), and the group sound was more earthly, bridging Laurie Anderson's musical theater and dream-pop. The sophisticated, almost ambient Stars On E.S.P. (1996), was reminiscent of Brian Wilson's productions but in a skewed, unorthodox way. Defever's arrangements did not shun the obvious: they recreated the obvious in another dimension.

Others included: Illinois' Moon Seven Times (1), featuring Lynn Confield, who specialized in ethereal madrigals that boasted the spiritual depth of a raga on Moon Seven Times (1993); Congo Norvell, led by former Gun Club's guitarist Kid Congo Powers and vocalist Sally Norvell, who gave one of the best imitationsof the Cowboy Junkies with their Lullabies (1993); Boston's Helium (1), led by Mary Timony, who bordered on feedback-pop on Dirt Of Luck (1995); Ohio's Elysian Fields, fronted by Marlene Dietrich-ian vocalist Jennifer Charles, with Bleed Your Cedar (1996); etc.

The atmospheric ballad, 1990-99

Whether it was "slo-core" or simply slow pop, the influence of alt-country or a by-product of psychedelia, the slow, atmospheric ballad became fashionable again.

Los Angeles' Idaho (2), i.e. singer Jeff Martin and guitarist John Berry, were both the most existential and the most psychedelic. Year After Year (1993) was a set of suicidal psalms imbued with documentary lyrics and recited in a pensive tone halfway between Leonard Cohen and Lou Reed. Martin's indolent pessimism reached new heights of sweetness on This Way Out (1994).

Acetone (1) continued the tradition of (in reverse chronological order) Dream Syndicate, Television, Neil Young, Grateful Dead with collections of transcendental pseudo-country ballads such as Cindy (1993).

Pennsylvania's acoustic quintet Low Road (1) wed the aesthetic of slo-core to country music on The Devil's Pocket (1994).

That abyss of gloom got rather crowded: Los Angeles' Love Spirals Downwards, who concocted a gothic/exotic/medieval/spiritual variant of the dream-pop cliches made popular by the Cocteau Twins and by Dead Can Dance, for example on Ardor (1994); Los Angeles' Spain, with The Blue Moods Of Spain (1995); Virginia's Drunk, with A Derby Spiritual (1997); etc.

Texas' American Analog Set (1) advanced the oneiric sound pioneered by Galaxie 500, especially on their second album, From Our Living Room To Yours (1997).

New York's trio Calla (1) sculpted shadowy melodies that slowly crept out of their fragile envelopes on the stark and stately Calla (1999), a softly-hallucinated music reminiscent of Ry Cooder's soundtracks and Calexico's desert ambience.

Seattle (and the Northwest in general) originated a close relative of "slo-core", a form of "textural rock" that hanged somewhere between the extremes of roots-rock and post-rock, and emphasized non-linear guitar-based soundscapes. Built To Spill (13) were the reigning champions of the genre throughout the decade. Formed in Idaho by guitarist Doug Martsch, with Caustic Resin's guitarist Brett Netson and Lync's rhythm section, Ultimate Alternative Wavers (1993) was mostly a guitar tour de force, but already displayed their slovenly, messy and noisy fusion of Neil Young, Grateful Dead and Sonic Youth. There's Nothing Wrong With Love (1994), instead, focused on structure, constraining Martsch's imagination. Perfect From Now On (1997) summed the two, granting the guitar several degrees of freedom while anchoring it to a spectacular group sound (the Spinanes' drummer Scott Plouf, Nelson's bass, cello, mellotron and synthesizer). These articulate and elegant compositions relied both on lengthy hypnotic jamming and on simple, manageable form. Martsch's relentless guitar ruminations created the noise-rock equivalent of John Fahey's "primitive guitar": introspection, meditation on the meaning of life, contemplation of the universe, and worship of the absolute. Keep It Like A Secret (1998) simply channeled that creative force in the format of the rock song. When Built To Spill finally returned to the science of abstract jamming, on You In Reverse (2006), its blend of pensive transcendence and manic depression sounded like the perfect soundtrack for the zeitgeist of the new century. Martsch's guitar had a unique way to penetrate the inner core of a song's melody and transform it into a cathartic experience. Marstch's tormented solos were the antidote to an era that increasingly strived for simplicity and superficiality.

Silkworm (2) boasted the depressed noise of guitarists Joel Phelps and Andy Cohen. Cohen's introverted mood and neurotic guitar dominated In The West (1993) and Libertine (1994). Pared down to a trio after Phelps' departure, Firewater (1996) veered towards the distorted, metaphysical folk-rock of Dream Syndicate and Neil Young, while highlighting the creative rhythms of drummer Michael Dahlquist and bassist Tim Midgett. Developer (1997) was another subtle essay of musical imagery, and perhaps even more arduous.

Red Stars Theory (2) turned Built To Spill's brainy trance upside down, emphasizing the trance, on their mostly-instrumental albums But Sleep Came Slowly (1997) and especially Life In A Bubble Can Be Beautiful (1999), which fused psychedelic, chamber and country music. Their songs were amoeba-like pseudo-jamming lattices that freely elaborated on a theme relying more on atmosphere and feeling than on structure or dynamics.

The legacy of slo-core was still being felt at the end of the decade on countless recordings: Fuck's Baby Loves A Funny Bunny (1996) and Half Film's East Of Monument (1998) in San Francisco; Kingsbury Manx's bucolic Kingsbury Manx (1999) in North Carolina; etc.

Built To Spill's best pupils were Seattle's Death Cab For Cutie (1), whose painstakingly detailed stories of alienation and defeat on Something About Airplanes (1999) employed the "textural" technique of the masters.

British transcendence, 1995-97

In England, Drugstore's Drugstore (1995) was a work of subtle seduction a` la Cowboy Junkies and Mazzy Star.

Mojave 3 (1), the new project by Slowdive's vocalists Neil Halstead and Rachel Goswell, were modern bards that harked back to the golden age of country-rock and folk-rock (Bob Dylan's Blonde On Blonde, early Donovan, Leonard Cohen) but added a metaphysical dimension. Ask Me Tomorrow (1996) and especially Excuses For Travellers (2000) were devoted to folk and country ballads that a lacerating pain had emptied of all energy and filled with a zen-like acceptance of the mystery of life.

Movietone (1), the project of Flying Saucer Attack's vocalist Rachel Brook and Third Eye Foundation's guitarist Matt Elliot played melancholy twilight ballads a` la Mazzy Star on Day And Night (1997).

Tram's Heavy Black Frame (1999) still revealed the ghost of Nick Drake behind slo-core's agony.