An anxious America gets set for life after Oprah

There will be tears – lasting several days, probably, and culminating in an epic sob-fest that will have middle America breaking out the Kleenex for most of next Wednesday afternoon. For nothing, it seems fair to predict, will do justice to Mrs Oprah Gail Winfrey quite so splendidly as the manner of her parting.

Crowds began descending on the United Centre in Chicago in the early hours of yesterday, in department store clothes and sensible shoes. They were clutching golden tickets that marked them out as being among 20,000 lucky fans who would witness a vast arena show entitled: "Surprise Oprah! A Farewell Spectacular!"

So begins the end of an era. Extended highlights of the star-studded "spectacular" will be broadcast next Monday and Tuesday. Then, on 25 May comes the grand finale: the last ever episode of Oprah, the talk show which changed television and placed its singular host at the epicentre of popular culture for the best part of a generation.

Winfrey has decided to leave her leather sofa after 25 years and more than 4,000 episodes. At the age of 57, with billions in the bank and an annual income estimated by Forbes at $300m, she is quitting the talk treadmill, moving to California from her native Chicago, and reinventing herself as a hard-nosed TV executive.

The next chapter in Oprah's story will revolve around OWN, an entire cable TV network fashioned in its founder's celebrity-friendly, feel-good image. Since launching in January, the channel has been beset with difficulties; its ratings are floundering, and two chief executives have recently been sacked.

Oprah's forthcoming attempt to turn it around is perhaps destined to show whether the historians of tomorrow will agree that Winfrey's unique place in the American psyche really does, to quote a famous Vanity Fair profile, give her "more influence on culture than any university president, politician, or religious leader, except perhaps the Pope".

But first, that fond farewell. For days now, fans have been treated to extended highlights of a career which began in 1986, when she slipped into a lurid pinky-purple outfit, emptied half a can of ozone-destroying hairspray, grabbed a microphone the size of a Mr Whippy cone, and welcomed viewers to the first ever Oprah Winfrey Show.

Since then, life's been a touchy-feely roller-coaster of emotions and celebrity revelation. Viewers have seen Michael Jackson cry and Tom Cruise jump on sofas. They've seen Whitney Houston discuss her cocaine addiction, heard a newly famous Susan Boyle sing, and been introduced to a fresh-faced young senator called Barack Obama, who Winfrey reckoned could very well be going places.

This week, Oprah has already wheeled out such old favourites as the Duchess of York, who revealed that she still harboured feelings for Prince Andrew ("I wish we never got divorced!") and her "most controversial guest ever", author James Frey, who five years ago was found to have fabricated the memoir Winfrey had helped turn into a bestseller.

Her arena show was meanwhile scheduled to feature the proverbial Who's Who of guests, according to its producer Sheri Salata, who promised reporters that dozens of "celebrities from film, television and music" had responded to invitations to appear with "a resounding yes".

Next Wednesday's final show at her studio, which sits on a road recently renamed Oprah Winfrey Way, is meanwhile rumoured to feature close friends from the presenter's childhood, influential figures from her private life (such as boyfriend Stedman Graham) and a quorum of Hollywood stars including Will Smith and his extended family.

Together, they will provide a fitting tribute to the cult of personality that has made Oprah the most powerful woman in entertainment. For she has a singular ability to not just probe A-list guests but also to allow viewers to share her personal struggles. Over the years, fans have watched Oprah come to turns with her impoverished and abusive childhood. They have seen her confront taboos such as sex abuse, addiction and infidelity, and reunite with long-lost family members. They have watched her waistline expand and contract. And they have heard her spout endless psycho-babble in an effort to show viewers how to "Live your best life".

Winfrey's show has remained ahead of the crowd by making its most intriguing property the one that rival programmes can never get hold of: Oprah herself. It is no coincidence that she was the first talk host to walk among her audience, positioning herself as one of them. And we should not be surprised that her most-watched episode was neither an agenda-setting "exclusive", nor a heart-warming real-life story, but the 1988 episode when newly slim Winfrey appeared onstage with a red cart containing 67 pounds of fat (the amount she had lost on a diet). It attracted 62 million viewers: one in four Americans.

Oprah has since been able to leverage her success as a chatshow host into a sprawling business empire. She began publishing magazines and websites, endorsing ranges of clothes and flogging diet products. Her ability to exercise an almost magnetic hold on the hearts, minds and wallets of middle America has been dubbed "the O factor". It's that which has also helped Oprah, perhaps more than any contemporary figure, cut across America's racial divides. As one of the first black celebrities who white suburban housewives admired, she has achieved change through conversation. In her first season, Winfrey taped a show in Forsyth County, Georgia, where not a single African-American had lived for 75 years; today, it has 7,000 black residents.

Not everything has gone smoothly, of course. In recent years, in common with most network TV shows, average viewing figures for Oprah have declined, to roughly half their peak of 15 million. Readership of O magazine is down. And OWN has so far been an unmitigated disaster.

Despite being financed to the tune of $215m dollars by the Discovery Network, which owns a 50 per cent stake, Winfrey's cable channel has attracted just 300,000 viewers to its prime-time shows (and half that in daytime) since launching in January. Announcing the sacking last week of Christina Norman, OWN's second chief executive in five months, Winfrey confessed that the channel is "not where I want it to be".

Once she leaves Chicago, she intends to knuckle down. In a troubled market, making a success of OWN will will take every ounce of the O factor she can summon up. But given Oprah's track record, only a fool would bet against her.

Oprah through the years

1954

Oprah Gail Winfrey is born on 29 January in Kosciusko, Mississippi

1973

Aged 19, Oprah becomes the first African-American presenter on Nashville TV network WTVF and the youngest person to co-anchor its prime-time news show.

1984

Oprah moves to Chicago to host her own morning chat show, 'AM Chicago'. It's renamed a year later and 'The Oprah Winfrey Show' is born.

1985

She stars in Steven Spielberg's The Color Purple, which receives 11 Oscar nominations, including a Best Supporting Actress nod for Oprah.

1986

'The Oprah Winfrey Show' is syndicated on 120 TV channels across the US.

1988

Oprah buys the studio which produces her show for $10m and renames it Harpo Productions ("Oprah" spelt backwards). She is the third American woman to own her own studio.

1988

Oprah wheels a "wagon of fat" into her studio to represent her 67lb weight loss after following a liquid diet.

1993

President Clinton passes the "Oprah Bill", which creates a national database of convicted child-abusers. It comes two years after Oprah revealed she was abused as a child.

1993

Oprah nabs a rare interview with Michael Jackson, who claims for the first time to suffer from the skin disorder vitiligo. It is watched by more than 90 million viewers in the US alone.

2000

'The Oprah Winfrey Show' racks up a total of 40 Emmy award wins. Two years later Winfrey would receive the Bob Hope Humanitarian Award on Emmy night.

2004

2004 Oprah gives 276 audience members a free car each (collectively worth $7M) in her first 'surprise' special.

2005

Now worth approximately $1bn, Oprah becomes the first black woman to enter the Forbes billionaires' list. Later that year she scores one of the most bizarre celebrity encounters of the year when Tom Cruise spontaneously jumps up and down on her sofa to declare his new-found love for actress Katie Holmes. Oprah later describes the now infamous 'couch incident' as one of her talk-show's most shocking moments.

2006

During a live broadcast in January, Oprah uncharacteristically berates author James Frey for lying in his memoir 'A Million Little Pieces', which she had endorsed through her show's influential 'Oprah's Book Club' slot (an endorsement by Oprah has been known to increase book sales five-fold).

2007

Plans to create OWN: The Oprah Winfrey Network are announced, and Oprah endorses Barack Obama's Presidential campaign.

2010

After recording more than 4,000 episodes The Oprah Winfrey Show begins its 25th and last season, to be broadcast in 145 countries. Between 2009 and 2010, the programme reached a weekly average of 40 million viewers in the US alone.

2011

Oprah launches OWN on 1 January and sets the date for The Oprah Winfrey Show's final airing, 25 May. In March, O magazine states that Oprah's show has welcomed more than 28,000 guests and 1.3 million audience members in the past 25 years.