Two years. A billion dollars. Sixty million votes cast in the primary alone. An election that started out in a country scorched by the fierce heat of the Iraq war ending in the frigid reality of a once-in-a-generation economic slump. A contest that opened with the promise of the first woman president ending in the apparently inevitable elevation of the first black man to the White House.

There’s a paradoxically anticlimactic feeling about election days. All that effort, all that money expended around the clock for years in an effort to influence what happens on this day ends in a period of almost eerie silence.

The heavy guns of campaign speeches and television advertising are muffled. The news turns briefly to other stories as campaign reporters who have checked in and out of hotels in the early hours every morning for weeks finally get to sleep in. The candidates can do no more than anyone else – simply show up and vote quietly in their designated polling station.

It’s a sacred, almost sacramental rite in a democracy. The citizens line up to exercise their terrifying power while the men who might rule them can only sit and wait. This contrast between the heat of the campaign and the light of election day is always most powerful in America, where the stakes are highest, the contests longest and the expenses greatest.

But there haven’t been many days preceded by more energy and freighted with much greater historic significance than this one.

By some time early tomorrow morning Americans will, in all probability, have ended 216 years of presidential rule by white males. Either that, or they will have contrived to deliver the greatest upset in the history of their democracy – greater even than Harry Truman’s famous win over Thomas Dewey in 1948 – and the consequences of such an upset might be almost as historic as a victory for Barack Obama.

Much ink will be spilled dissecting what the election of an African-American means for the country and world. Odd though it might seem to say it, the historic symbolism of a win for Senator Obama might in the end matter much less than its practical political implications. His Democratic Party seems about to seize the reins of political power in a way no party has done at least since Ronald Reagan’s Republican victory in 1980. Barring something unimaginable, by tomorrow Democrats will have more seats in the Senate than they have had in the past 30 years. They will extend their dominance of the House of Representatives.

At home and abroad they propose to end the period of conservative dominance that began back then and push the US sharply to the left.

A President Obama will have comfortable majorities in both houses of congress for his domestic policy initiatives: a redistributive tax plan that could push top US marginal tax rates above those in most of Europe; a comprehensive health insurance proposal that will expand dramatically the reach of medicine to some of the poorest Americans; an assault on globalisation through higher taxes for US companies that shift business overseas, a toughening of the rules by which America trades with the rest of the world, and a rollback of the financial and industrial deregulation of the past 25 years, including significant new powers for trade unions.

The new era of Democratic dominance would reach deep into Americans’ lives. With such a large majority in the Senate, Mr Obama, if he is elected president, would be able to appoint judges in the activist mould of liberal judicial philosophy. These are jurists who believe not just in ruling on the constitutionality of individual laws and actions but, in the tradition of Supreme Court justices appointed in the 1930s and 1960s, to direct political progress on the sorts of social issues that other countries leave to parliaments and their people. Abroad, a Democrat-led government would seek to refashion America’s image in the world. On issues such as climate change, Guantanamo Bay and the treatment of detainees, Iraq and the broader war on terror, an Obama Administration would try to limit the exceptionalism that has defined America for much of its history.

It would be a remarkable departure. Not least because only four years ago, in what was also deemed an historic election, that vision of government’s role and purpose seemed to have been buried for ever. When George Bush won a second term, marking the fifth Republican victory in the past seven presidential elections, there seemed little prospect that the era of conservative dominance would end any time soon, let alone be brought crashing down in the final days of his own presidential term.

And you certainly would not have found many pundits who would tell you that the person to do it would be an eloquent young black man who had at that point never served a day in public office outside the statehouse in Springfield, Illinois.

Times Recommends

• Resist urge to throw voters red meat
• Slay sacred cows and be candid
• We cannot let these 100 deaths deflect us