It was one of the most expensive campaigns in New York history.
Republican Congressman Rick Lazio spent $33 million over five months in an effort to defeat Hillary Clinton, raising most of it from outside the state. Mrs Clinton spent $26 million over 16 months.
From the start, Mrs Clinton's was an unlikely quest; a woman born in Illinois who spent the bulk of her adult life in Arkansas, a woman whose ambitions took second place to her role as a political wife for 24 years.
But her determination to build an independent life after the White House took hold two years ago.
During the time the US Senate was considering her husband's impeachment, Mrs Clinton sat down with her political adviser, Harold Ickes, and New York Congressman Charles Rangel to discuss the possibility of her running for the Senate.
It would be unprecedented; in the 1940s Eleanor Roosevelt had been approached about running for office, for the same New York Senate seat, but had rejected the idea, choosing instead to make her mark at the United Nations.
No First Lady had ever run for office. In addition, there was the not insignificant matter of Mrs Clinton's residency. She had never lived in New York, a diverse state known for the roughest of rough-and-tumble politics.
The pundits said the idea was ridiculous. Even New Yorkers weren't too keen on the idea. But Mrs Clinton moved to New York, buying a $1.2 million house in suburban Westchester County.
She launched a "Listening Tour" and promised to visit every single one of the state's 62 counties. From the northernmost scenic reaches of the state that border Canada to the grimy streets of the South Bronx, Mrs Clinton hit the road to talk to voters.
It was a stunning 16-month campaign. While her 43-year-old opponent took a four-day vacation in September, the 53-year-old Mrs Clinton worked 20-hour days. In person, she was far warmer than people had expected.
"She seemed to have the Buffalo phone book memorised," said Eugene Capicotto, president of a local union, who travelled with Mrs Clinton upstate.
Another union official told the New York Daily News that Mrs Clinton did so well in conservative upstate because she did not come across as "too aggressive". Her margin of victory - it may amount to 800,000 votes when the last vote is counted - surprised even her most ardent supporters. And what about women? One of the curious aspects of the campaign seemed to be the reluctance of women to support Mrs Clinton. Pollsters and pundits said they were among her harshest critics.
In the end, women overwhelmingly supported her, giving her a 12 per cent gender gap. She won male voters by just 2 per cent, but women constituted 54 per cent of the voters in New York.
The big surprise was upstate, traditionally Republican territory. Mrs Clinton did so well in upstate for two reasons. The first is that she continually discussed an economic revitalisation plan for the upstate economy, which has been battered in recent years. Mr Lazio offered no such innovative programme.
The second, less tangible, factor was Mrs Clinton herself. At heart, she is in many ways a very traditional woman. She is a mid-westerner, conservative in dress and demeanour and not at all like the sharp-edged Manhattan feminist stereotype that upstaters were expecting. When they met Mrs Clinton, those conservative housewives identified with her.
On the American political landscape, Senator Hillary Clinton is the most exciting figure to come along in years.
PA adds:
After a day at their home in Chappaqua, President Clinton and his daughter, Chelsea, accompanied Mrs Clinton to Manhattan early yesterday to celebrate her victory.
Cheers echoed through the cavernous atrium of the Grand Hyatt Hotel as the First Lady's supporters, watching televised reports, learned she had won.