Long before Spike Lee, Jim Jarmusch or Alex Cox, Sayles was scripting, acting in and directing movies whose influence far outstripped their sketchy sets and miniscule budgets. Yet he is also an ace "script doctor." Able to transmute ideas or best-sellers into vehicles that will work when filmed, script doctors are among Hollywood's most valued offscreen figures. Sayles has used his writing clout to bankroll films of his own - movies his mainstream employers would never think of backing.

Those films have covered a lot of ground; from post-'60s political fatigue (1980's The Return of the Secaucus Seven) to the first movie about a black from outer space (1984's The Brother from Another Planet). Sayles never tackles the same topic twice. But twists of class and power permeate his scripts as much as they do the novels of Jackie Susann. So, however, does a dry wit, which has won him fans around the globe.

From stars like actress Rosanna Arquette through technicians such as like Spike Lee's cinematographer Ernest Dickerson, Sayles has given many a well-known name their first movie break. And many of his most ardent admirers are other artists. They range from Jodie Foster (currently using one of his team to produce Little Man Tate, her directing debut) through singer Bruce Springsteen - who hired Sayles to produce and direct his first pop video.

Born in Schenectady, New York, 39 years ago, Sayles was a teacher's son. Initially, he wanted to be a novelist (his first book, Pride of the Bimbos, was about an all-girl baseball team.) Sayles financed three novels with work in factories, hospitals and a meat-slicing plant. But he was soon seduced into writing scripts for B-movie maker Roger Corman. Screenplays like his Piranha (1978) and The Lady In Red (1979) displayed a knack for infusing cheap genre pics with snappy dialogue and a stylish edge. And a suprise MacArthur Foundation Award - America's so-called "Genius Grants", anonymously conferred - enabled Sayles to start making movies on his own.

His first was The Return of the Secaucus Seven: a film about the reunion of seven 1960s graduates. The slim, gentle movie became an underground hit. Eventually, it also altered the entertainment mainstream: a direct line can be traced from its script to Lawrence Kasdan's The Big Chill and television's thirtysomething. But while others recast its anxieties about age and change into yuppie angst, Sayles was scrambling to tell different stories. Over the next four years, he made three films: Lianna in 1981, Baby, It's You in '82 and, two years later, The Brother from Another Planet.

All were quirky, subversive projects. In Lianna, a well-off faculty wife finds independence tough when a lesbian affair spells the end of her marriage. In Baby, It's You, a smart girl falls for the son of a garbageman - and discovers how economic destiny undercuts romance. In The Brother, made for $20,000, a mute black alien wrestles comically with life in mid-'80s Harlem.

By 1987, Sayles was finally able to film the first script he had ever written: Matewan. The true story of a 1920 mining dispute in America, Matewan dealt with the unity forged between blacks, poor whites and Italian immigrants. Comic as well as inspirational, it won the writer-director comparisons to the great John Ford. In 1989, he followed it with Eight Men Out, another historic tale. The Eight Men were members of Chicago's "Black Sox" baseball team - national idols who helped fix the World Series of 1926. Both Matewan and Eight Men Out offered more than action, humour and suspense; they were meditations on national truths versus national myths. They brought Sayles' personal projects a new degree of critical and industry respect.

Today, Hollywood recognises John Sayles as a top-flight writer. NBC TV supremo Brandon Tartikoff personally commissioned him to pen a primetime series, Shannon's Deal. And the films Sayles scripts for studios now feature real stars and issues instead of period gangsters and cannibal fish. Once a beyond the pale "politico". he can now write films for the likes of Burt Reynolds and director Bill (Local Hero) Forsyth. But Sayles never leaves his conscience in the parking-lot. He also scripts work like the TV movie Unnatural Causes - an expose of Vietnam War toxin Agent Orange.

This week, however, John Sayles sits in an underfurnished room in Cincinnati, Ohio - the most old-fashioned of midAmerican towns. Thanks to its vintage architecture and scenic surrounding hills, this usually-quiet city has found itself hosting three separate movies. Palace Pictures' period thriller A Rage In Harlem is encamped on the "bad side" of town; Jodie Foster's Little Man Tate has comandeered the working-class suburbs. And the crew for a new John Sayles film - his seventh - is scouting locations which range from City Hall to low-rent apartments.

That film is City of Hope (initially called The Hope of the City), a civic political drama played out through the lives of two young men. In a choice which resonates with recent American crises, one man is black and the other is Italian. The black city councillor is played by Joe Morton - the Brother from Another Planet. His Italian foil will be Vincent Spano, the romantic "Sheik" of Baby, It's You.

The action, says Sayles, involves "probably 40 characters you have to know". Yet he plans to wrap it in under five weeks. In fact, as the new production company (called Esperanza, or "Hope") unpacks around him, the man at its centre radiates reassurance and calm. Partly, it's just his physical presence. Sayles, who acts in all his films, is considered a bit of a heart-throb in American left-wing cicles. His athletic, six-foot-plus frame overflows the office chairs. And he smiles very easily - Sayles hardly fits the stereotype of a stolid, crusading auteur.

History fascinates him, and his conversation ranges from union lore to sports. But the Sayles love of hidden stories from the past has nothing to do with nostalgia. The new film, he tells me, embraces the past in the present. "It's about ethnicity and family and race and-if-the-Mayor-doesn't-get-in-your-cousin-Vinnie-will-lose-his-job." Spano's character flees the world of patronage politics just as Morton's is trying to break in. But two crimes unexpectedly up the ante, inflaming confrontations of race, age - even sexual choice.

It's less about smalltown USA than broader Sayles concerns: making the right choices in life and working towards some kind of community. "Yeah. It's the thing of who do you represent - your ethics or those people who elected you to speak for them? It's about that real circle of blood and pressure and loyalties. Not the TV-commercial community people haul out when there's something to sell."

Over the past twelve months, Sayles has written and put together the picture which starts to roll this week. But he also finished Los Gusanos, a novel about Cuban refugees he's been working on for ten years. Then there was the pilot and subsequent episodes of Shannon's Deal. How come Hollywood's Odd Man Out accomplishes more than its most driven denizens? Patience and perseverance, he says. "I'm lucky, because a lot of things that put pressure on other people don't matter at all to me. I still live in Hoboken, New Jersey. I still swim at the local pool, play basketball in my local gym."

But nothing gets simpler, he adds. "You just learn better ways to cope. It's not easier to raise money, it's not any easier to get your pictures seen -in fact, that's a little harder than it was five or six years ago. And writing is not any easier. It all requires a sort of Zen discipline. You find out how you can stay loose, but concentrate at the same time."

Pragmatism, says Sayles, also plays a central role in any successful artistic life. "Talent is just the bottom line. To get what you want, you have to master a lot of other things. You have to learn fast from your mistakes, and develop some real instincts."

"That's a lot of what Eight Men Out was supposed to be about," he adds. "At one point this famous pitcher says, 'I always thought it was talent that made the difference'. He's realising that ballplayers come and go; what stays is these guys who own the game. That's as true in music and film as it ever has been in sport. Talented people have their talent, it burns for awhile, then it goes. And very rarely do they achieve any real power because of it."

No matter how great their critical acclaim, Sayles knows it is not his movies which have brought him the real Hollywood clout. It's the magic he can work for others. "These days, big studios just go for two or three home run shots a year. Everything else is, 'Put lots of stars in this one - then maybe it'll catch fire'. Or, if there's a hot genre like horror, OK, then throw out a couple of those."

"What they won't even consider," he says, "is small - in their terms - eight or nine million-buck movies. Even if it is a great script or interesting subject matter." The value of Sayles to this cut-and-dried world is that, even when he disagrees, he will take its values into account. "I'm often asked, for instance, to rewrite someone else's script. And they're not still with that person because the piece was autobiography. So the writer froze on some detail - because 'that was the way it happened'."

Sayles shrugs his broad shoulders. "Reality and good storytelling are very seldom the same. To take stuff out of people's heads, to make it dramatic, you fictionalise."

He's also very aware that audience perceptions have changed. "People now have less patience, they want to be told everything. There's a story about George Miller, who made the Mad Max films, watching some kids with a VCR fast-forward through all the dialogue parts. And deciding to make a movie where they would never have to do that. Whether it's action films or rock video, that beat keeps being turned up."

These changes, says Sayles, are basic to all our lives and their electronic baggage has to be taken into account. "The media is now like a drug, a drug with two separate effects. One is to zone people out and lie to 'em in a pleasant way. Just take up their time so they don't sit around saying, 'I'm fucked up - I'm gonna go break someone's window and take their stuff!' But the other thing it does is it creates expectations. And the expectations it creates are not gonna be delivered."

Sayles sees this as central to understanding modern politics, which is where City of Hope comes in. "You have to understand that it's not just 'leaders'. That it's also in you and in the people around you. Reagan and Thatcher did not just come along and hypnotise people. People wanted this; they were desperate for life to really seem simpler."

And what matters very much in this world is the role of information. "Control of information is so much of what power is based on. Things start to rot once you get paranoid about that control. You get to a point where people are so paranoid about the truth they lie about practical matters. You know, 'Sure the water's safe!', 'Sure, we met the quota!' When, of course, they haven't done shit. But they can't say that, or they'll really be out in the cold."

Sayles has been both successful and subversive not least because he recognises what he cannot control. Yet, within those parameters, he guards his work fiercely. "So much of what's made now as movies is just advertising. Demographics come first - that's why the film gets made a certain way. And I've never wanted to be in the advertising business."