Yet now, in the final hours of the campaign, Clinton’s poll lead has not widened. It has narrowed, and Donald Trump could even snatch victory. While most experts consider this unlikely –just as they considered his original nomination as Presidential candidate unlikely - the closeness of the campaign, as much as the vitriol exchanged between the two contenders, is chilling. It is testimony to a deep distrust, bordering on loathing, for millions towards Mrs Clinton and a damning verdict on the persona of both candidates.
The election has huge significance for the rest of the world, not only in terms of US diplomacy and geo-politics – particularly towards a more assertive and manipulative Russia under Vladimir Putin, but also for America’s future trading relationships. A Trump presidency could see a shift away from free trade towards a more protectionist stance. He has made clear that he will introduce not only tighter border controls but also much closer scrutiny of foreign take-overs and the movement of plant and capital from the US to countries where labour and manufacturing costs are cheaper.
For those outside the US all this can be hard to fathom. The breadth and intensity of heartland America’s antipathy to what is seen as an out-of-touch Washington elite is almost palpable. And Trump has conveyed an opportunity of vengeance against this entrenched and privileged group that for years, he charges, has governed in a manner to best secure their perks and privileges.
Mr Trump’s appeal is directly to this insurgency. In some respects it is similar to the vote by millions here in the UK in the referendum on our EU membership, widely seen as a rejection of the Westminster elite and its caravan of lobbyists, beneficiaries and apologists. A similar mood of voter anger and anti-establishment feeling is evident across many countries in continental Europe – France in particular, but with signs of growing revolt in Germany, too.
The support that Trump has inflamed by his posturings and the prospect he holds out of a Washington clear-out suggest that this mood will not end when the final votes are cast tomorrow. While this presidential campaign seems to have been going on for far too long, the disputatious mood in America has further to run. No matter who emerges as the ‘victor’ in this ugly campaign, it portends a period of tumult and potential instability - one that will cast a troubling shadow around the world.