By Mike Carlson
US sports analyst
Millions watch the annual Super Bowl - a money spinner for advertisers
The Super Bowl, the championship game of America's National Football League (NFL), is the world's richest single sporting event. Nearly half of America will watch it on television on Sunday 3 February.
It's the most costly advertising platform in the world: each 30-second commercial will sell for $3m. There is no other day in the American calendar which unites so much of the country.
It hasn't always been so. Today the NFL may fairly claim to be "America's game" - even though baseball has always been referred to fondly as "America's pastime".
But not so long ago, pro football was not even gridiron's glamour game - that honour belonged to the college version of the sport.
First Super Bowl
Their relationship was similar to the traditional status of British rugby. College football was the equivalent of rugby union, an amateur game played on Saturdays by gentlemen. The college "bowl" games, played on New Year's Day, in sunny parts of the country between teams from different regions who normally never met during the autumn season, were the equivalent of rugby's internationals.
Pro football, in those days, was America's rugby league: played primarily in the industrial north, on Sundays; a hard game played by hard men.
The first Super Bowl took place in 1967. At that point it was already clear that pro football was a business about to boom, thanks to television. No sport has ever been better suited to the small screen than American football, with its breaks between plays to invite analysis, and utilise technological innovations like instant replay, split screens, and isolated cameras.
Colts and Giants
But the game that first showed pro football's potential to hook a mass TV audience took place almost a decade earlier, on 28 December 1958, in New York's Yankee Stadium, when the New York Giants met the Baltimore Colts for the championship of the NFL.
The NFL players with the highest public profiles were those who had been college stars, at big universities, and the Giants had more of them, particularly Frank Gifford, whose good looks and effortless grace at the University of Southern California inspired Frederick Exley's classic novel, A Fan's Notes.
I grew up in nearby Connecticut. My father, grandfather, and uncles were Giants fans; in fact, my father had played in college against the Giants' star defensive end, Andy Robustelli, who'd come from little Arnold College in nearby Bridgeport.
But "fan" meant something different then. When these men, aged from 30 to 55, watched the game, they didn't wear replica jerseys, paint their faces, or discuss their fantasy teams. The idea grown men might follow a game like children would have struck them as insane.
The Colts, in fact, were closer in spirit to my father and family. Their quarterback, Johnny Unitas, with his buzz-cut hair and high-topped boots, had played for little-fancied Louisville University. He played semi-pro football on Pittsburgh fields so devoid of grass they were sprayed with oil to keep the dust from rising.
The Colts had their own Italian defensive end, the fierce Gino Marchetti, playing alongside Art "Fatso" Donovan, and Eugene "Big Daddy" Lipscomb, a six-foot-five, 300-pound behemoth (by 1950s standards, that is - for today's game he'd be considered undersized.)
Unitas led his team back into the game, at the end of normal time
The Giants had qualified for the final by beating the Cleveland Browns two weeks in a row, first in the season's final game, which brought them level at the top of their division, and then in a one-game playoff.
Their defence, anchored by middle-linebacker Sam Huff, closed down Cleveland's star runner, Jim Brown, (the future Hollywood actor) who recorded the worst performance of his career.
The championship opened with the Colts dominant. They led 14-3 at the half. But the Giants struck back in the second half, taking a 20-17 lead late in the game.
Unitas calmly led the Colts back. He had a pass-catcher, Raymond Berry, who ran precise patterns: Unitas could throw the ball knowing exactly where Berry would be. They combined on three consecutive pass plays, covering 62 yards. With the game about to end, kicker Steve Myrha booted a 20-yard field goal, levelling the scores at 20, and sending the contest to "sudden death" overtime. The first team to score would win.
Only quick-thinking by a television staffer, who ran on the field like a drunken fan to delay the game, allowed technicians to find and re-connect the cable
Extra time was a football first. Traditionally, gridiron games ended when the clock expired, and a draw was considered just reward.
But pro football needed a champion, and the idea of a soccer-style replay was never an option. The Giants won the coin-toss to receive the extra time kickoff, but struggled against the Colts' defence. They punted the ball away, and Unitas took over.
Keeping the Giants off-balance by combining runs and passes, he marched the team down the field. Then, America lost the television transmission. The foot-pounding of the visiting Colt supporters had knocked a cable loose.
Record television audience
Only quick-thinking by a television staffer, who ran on the field like a drunken fan to delay the game, allowed technicians to find and re-connect the cable. Then, before an astounding (for the time) 45 million viewers, Alan "the Horse" Ameche carried the ball into the end zone from a yard out, and the Colts had won.
I can still recall the whoops of my father, grandfather, and uncles as the game was won; a sound of amazed and excited relief, even though their team, the Giants, had lost.
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The game marked a turning point in many ways. It had attracted a record television audience, but the stadium had not actually sold out. Giants' owner Tim Mara would die a few weeks later, saddened by the result, but overjoyed at the rush of season-ticket requests that followed the contest.
The New York Times ran a magazine feature on Giants' linebacker Huff, and a CBS television documentary called The Violent World of Sam Huff would follow. People still loved their local college teams, but the pro game had announced itself as the better television spectacle.
Finally, the Super Bowl would cement pro football's new place in American consciousness. In the words of Tex Schramm, the former Dallas Cowboy general manager, "It was the time when people stopped doing and started watching".
On Sunday, more of them will likely be watching the Super Bowl than any show American has ever offered. And it all started with an overtime game half a century before.
Mike Carlson will be presenting BBC television's coverage of the Super Bowl on 3 February