It's just 30 years since Tommie Smith and John Carlos defiantly raised their black-gloved fists to the Mexican skies, 30 years since the less celebrated Lee Evans took to the Olympic rostrum wearing his Black Panthers' beret. Thirty years, and American sport is still plastering quietly over the race fissures in its corporate edifice.

This autumn, baseball has enjoyed a transfusion which has saved the great game from a lingering death brought on by malignant industrial relations and terminally ugly team owners. The most storied statistic in the sport, the home run record held first by Babe Ruth and then by Roger Maris, has been chased down and overhauled by two men, Mark McGwire of the St Louis Cardinals and Sammy Sosa of the Chicago Cubs.

McGwire looks like a bouncer at a pick-up joint, goateed and grim and built like a South African prop forward. He has forearms with a circumference of 17 1/2 in and he hits the baseball so hard that pitchers fear that one day he might drive a hole right through one of them.

And McGwire is America's boy. The son of a dentist who coached his son's little league team in leafy Los Angeles suburbia. Mark McGwire worries about child abuse and the erosion of family values, and he admonishes fans who tote autograph books on behalf of their offspring that they should be the heroes to their own children, not him.

On the last day of the 1987 season, when he needed one more home run to round off the season with 50 homers, he cried off the game to be beside his wife when she gave birth to their only son. They divorced a year later, but the business of the missed game and McGwire's decision to take a day's paternity leave refused to die in the public memory. A millionaire being with his wife during childbirth became the luminous testimony to the millionaire's virtue.

And so, when, one day earlier this summer, McGwire was chatting with reporters at his locker and one of them spied a bottle of androstenodione sitting pretty and half-full on McGwire's shelf, America was quick to forgive. The drug that turned little old East Germany into the German Drug Republic still isn't on the banned list of baseball. Big Mac was just looking after himself, wasn't he? Sensible and pragmatic.

This weekend, Mark McGwire crunched his 64th home run of the season, putting him one ahead of Sammy Sosa as the pair leave Maris' record (61 in a 162-game season) and Ruth's (60 in a 154-game season) behind them.

America rejoiced clamorously. This, after all, is still the land where Larry Bird (white) always made more money that Magic Johnson (black), where a white heavyweight, if you could find a good one (sit down Peter McNeeley, sit down) would be worth five times more than any black heavyweight. America's sports people are predominantly black, but the owners, the fans, the sportscasters and the quarterbacks are predominantly white. And from Ruth to Maris to McGwire, hitting a baseball out of a ballpark has been seen as the most quintessential American deed imaginable, something that causes suns to set and flags to flutter.

Sammy Sosa isn't an American and his story doesn't read like a Ronald Reagan homily. He was born and raised in the Dominican Republic, he wears jewellery which Liberace would find gauche and he collects sports cars by the herd. He plays for the Chicago Cubs, the team with the prettiest ballpark but the longest unbroken string of misfortune and mediocrity in major league sports in America. He's not corporate fodder and he's not middle America matinee idol material.

And yet anyone who loves sport should be rooting for him. If not for his body, which is chunky but free of the potions dreamed up by East German chemists, well, then for the essential romance of his story. His tale has that melting pot chime to it.

When scouts from the major leagues came fishing in his home town of San Pedro de Macoris 13 years ago, they noted two things: he could whack a baseball; he looked malnourished. The Texas Rangers gave him $3,500 to sign for them. He handed the windfall to his mother, keeping the price of a bicycle for himself.

The next spring, he left for America without a word of English and with a creaky knowledge of baseball's subtle tactics. He was traded twice before ending up in the ivy-clad haven that is Wrigley Field, Chicago.

One thing he knew was that he hadn't the luxury of learning baseball's intricate tactical nuances. Sosa tried to hit every pitch out over the fences, because he knew that the only way to make the big money he needed was to run up home run numbers which got him into the headlines. With a large extended family to support back in the Dominican Republic, he needed to make dollars quickly.

Last season he had his reward in loot if not in exposure. The Chicago Cubs, appreciating that despite the weight of their woeful history they were putting together a halfway decent team, paid him $42.5 million to stay with them for another four years. This year he has hit 63 home runs and the Cubs are stitching together their best season in decades.

Sosa's family have been transplanted to the north lakeside suburbs of Chicago. Sosa, the kid who bought his first bicycle with his signing on fee from major league baseball, has treated himself to a 60-foot yacht which he calls Sammy Jnr, displaying a total absence of the polished hubris which makes his rival Mark McGwire such a commercial patriot.

When you read about Sammy Sosa or tune in to the American coverage of the home run race between the two, it is impossible, without being wilful about it, to ignore the undertones of bias and crackling racial tension. Reverend McGwire is Mom's apple pie in a baseball uniform. Sosa is a slugging demon, and his origins, persistence, sheer vulgar hunger and clanking jewellery are a little, well - say it because they won't - a little too uppity for the palates of middle America.

This summer baseball, the sporting expression of the American pastoral, has revived itself apparently as a quiet rebuke to the pitter-patter of little knees on the Oval Office carpet. In an era when family values are wielded once again as a cudgel, Mark McGwire, freckled, wholesome and white, is the poster boy.

But Slammin' Sammy Sosa, late of San Pedro de Macoris, better represents the American dream as it existed before the corporate imagineers got their oily hands on it, and somewhere out there - beyond the corporate boxes and whitebread tiers of season ticket holders - is his constituency, not wheeling and dealing, but dreaming like he did.