The pirate radio stations of the 1960s are part of British pop folklore, but America had its equivalents broadcasting from the border with Mexico. And its most celebrated star DJ was the near-mythical Wolfman Jack.
Every DJ has their "radio persona" - a larger than life personality created to reach across the ether and plant itself in the imagination of the listening faithful.
The most outrageous - from America's Howard Stern to Britain's Chris Moyles - have come to be known as shock jocks.
Born 1938; died 1995
Became cult DJ on XERF 'border' radio - based on Mexican border
Renowned for gravelly voice, anarchic antics
Starred in 1973 film American Graffiti
Died of a heart attack
The daddy of them all is Wolfman Jack, the most outlandish, most thrilling and most elliptical disc jockey of the American 1960s.
Immortalised in George Lucas' breakthrough movie American Graffiti, the Wolfman derived from an era when radio's disembodied voice could be almost mesmeric.
His influence on radio today can still be heard... you just need to know what to listen for.
THE DJ PERSONA
Of course, Wolfman Jack wasn't born with that name. He was born Bob Smith and he grew up in the tough New York neighbourhood of Brooklyn. Neglected by his parents he sought succour and inspiration from the voices he heard on the radio at night beaming up from the Mexican border.
In his 20s he landed a number of DJ jobs on local radio stations where he experimented with a variety of bizarre and eccentric DJ personas.
Finally in the late 1950s, determined to take on border radio - the American-equivalent of Britain's off-shore pirate radio stations - he made his way down to Mexico to the great "border station" XERF and bought himself a show.
Amongst Bob Smith's heros were disc jockey Alan Freed, aka Moondog, and blues singer Howlin' Wolf, whose names formed the inspiration for his own alias, Wolfman, a name which debuted as early as the first show.
Alan Freed was credited with coining 'rock n roll'
"There was nothing as exotic, as mysterious and as forbidden as when I first stumbled across Wolfman Jack broadcasting from the border," says Nic Patowski, a teenager when he first tuned into station XERF. "He was unlike anything I'd ever heard before.
"You had no idea who he was or what he was but you knew whatever he was doing it was probably wrong. When you heard him you knew you'd unlocked the door to a really secret world."
Canadian-born DJ David Jensen, an early fan, compares Wolfman's character to something out of a Stephen King film.
"When I first heard him... I was thinking of old recordings of the blues singer Howlin' Wolf. He had this incredible confidence."
Much of Wolfman Jack's power and enigma lay in his voice. In the early 1960s most DJs both in America and in the UK presented their programmes in a straight, deadpan style.
But Wolfman Jack's rich, gravelly baritone was indefinable and otherworldly. He was hell-fire preacher, animal, beat poet, philosopher. He purred, he growled and he howled.
"The voice was almost scary," says Bill Crawford, author of Border Radio: Quacks, Yodelers, Pitchmen, Psychics, and Other Amazing Broadcasters of the American Airwaves.
"It was really scratchy and nasty and dirty and it was delicious. If you ran into someone on the street who spoke like that you'd assume they were a hobo or some kind of derelict. "He was more forbidden than listening to African-American DJs on the rhythm and blues stations."
Wolfman, the original shock jock
Wolfman was the precursor to the "shock jock" phenomenon, those irreverent, taboo-breaking DJs of the 1970s like Howard Stern and Steve Dahl.
But while Wolfman was edgy and his shtick was often kinky and provocative, he drew a strict line at being wilfully offensive. He believed passionately in preaching "more soul" to the world and he maintained a code of decency.
Broadcasting from the strange world of the Mexican border offered Wolfman Jack enormous power.
David Jensen said there was a mystique behind the voice
"The border is the part of America where the lines are blurred. Right and wrong, Mexico and the US, Spanish and English," says Crawford. This blurring of boundaries enabled Wolfman Jack to expose his audience to the sounds of African-American music which was not widely broadcast on US stations at that time.
His manager for over 20 years, Lonnie Napier, says: "Wolf loved rhythm and blues".
"Aretha Franklin, James Brown... They weren't getting much airplay in the US at that time but over on the border Wolf was allowed to play what he wanted."
Ray Bensen, lead singer of Asleep at the Wheel, recalled being on tour, getting into a car at 2am and turning on XERF. "You'd hear Louis Armstrong followed by the Robbins followed by Jimmy McGriff. He'd play it."
In an era free of the DJ mug shots we are so familiar with now, Wolfman Jack's listeners had no idea of the face behind the microphone. Many, like David Jensen, believed he was black.
"He could talk the soul language of a black man with the dialect," says Border Radio historian, Durell Roth. "I thought he was black for many years and that's the beautiful thing about radio, it's totally colour-blind."
THE MAGIC OF NIGHT
As the name suggests, Wolfman was a creature of the night. He loved the midnight hour, "the bewitching time" as he called it and the time when a hungering young audience could feed on his titbits.
Young people hanging out late in their cars would tune into his broadcasts and feed off his reckless, free spirit. And as his young fan base grew, Wolfman became the leader of a generational movement.
Lucas was a Wolfman fan
"The idea of teenagers having power was a new concept... and I think radio and Wolfman Jack had the power to bring us all together because we were all listening," says Nic Patowski.
Napier recalls the subtle spread of Wolfman's reputation while at a diner one night
"I saw this group of guys and they all had these T-shirts on and it had what looked like a huge target circle on it and this weird-looking character in the middle that kinda looked like a wolf and it said 'Have mercy baby'."
Among those teenagers hanging out at late-night diners and listening to the Wolfman's broadcasts was a young George Lucas, who went on to direct Star Wars.
Lucas responded to his call with one of the great American movies, the coming of age film American Graffiti, in which Wolfman Jack is a constant but mystical character.
THE 'X' FACTOR
Wolfman Jack's genius was his determination to maintain the enigma for so long. Invitations to appear in public flooded in soon after his unique sound hit the airwaves in the late 1960s, but Wolfman would invariably refuse. He insisted on keeping the magic of the radio persona he'd created. He didn't want to give people a concrete image of who he was.
The diner provided many fans
Lonnie Napier recalls the thrill of seeing Wolfman for the first time, having only ever known his voice.
"I knew he'd come in because I could smell his cologne all the way up the stairs. And then when I saw him I was just blown away. He was just bigger than life with his Beatle boots and his jet black hair and the goatee. He was better looking than Elvis."
Following his appearance in American Graffiti, however, Wolfman did start to let the mask slip. His credibility amongst teenagers led him to be the face for Clearasil acne medication advertising and he started to host television programmes like The Wolfman Jack Show and The Midnight Special.
Wolfman later developed a TV presence
But where he had been in control of his own destiny, on the border, he was now bowing to increasing pressure from the media to appear in public. For many of his fans, Wolfman's "outing" from the hidden world of the radio meant he had lost his edge. His own belief in maintaining the mystery and enigma of the voice in the radio-ether had been proven correct.
"Somehow it was a disappointment to see the man in the flesh," says David Jensen, "I wanted to carry on believing that he was a kind of half-human, half-animal creature. But I like to think that those radio waves he inhabited are still transmitting out there somewhere still today. He was a true icon."
Border Blaster: In Search of the Wolf is on BBC Radio 4 on Saturday 22 March at 1030 GMT, concluding the following week.