Four years ago I stood in Chicago's Grant Park, scene of infamous rioting during the 1968 Democratic National Convention, to hear Barack Obama's victory speech. I had flown over on the promise of what would be one of the most historic election results during my lifetime and wasn't disappointed.

Implicitly recognising the scale of his achievement as the first African-American president, Obama spoke to those who would “put their hands to the arc of history and bend it once more”.

Tonight's election is an altogether more prosaic affair. The audacity of hope has given way to the audacity of hype. But all US elections are momentous and I believe historians will look back on tonight as hugely significant for another reason related to ethnicity. This is the last English-American election. Naturally future elections will be conducted in English; but from 2016, the advantage may fall to the party that recognises what few people outside America have fully grasped: the world's leading superpower is becoming Spanish.

The speed of demographic change is dizzying. Never mind Mexican-Americans being a third of the US population by 2050; in Texas and California, America's two most populous states (and therefore the most electorally valuable), a majority of schoolchildren are Hispanic. These pupils' votes are American, but their mother-tongue is Spanish. In New Mexico, eligible Latinos constitute 55.9 per cent of the electorate.

The Hispanic vote will fundamentally and irreversibly change the tenor and tone of the election

Hispanics lean towards the Democrats roughly three to one – that is, decisively in terms of the overall result. Their vote, the fastest growing part of the electorate, is therefore precious; and so desperate for it will each party be that, come 2016, their pursuit of Hispanics is certain to be much more blatant.

In policy, the immigration reform pioneered by Ronald Reagan – which Obama has failed to deliver – offers potential electoral gold. In presentation, expect many more Spanish language ads, and whole campaign rallies conducted in Spanish. In personnel, both Republicans and Democrats will be tempted to field Latinos: Marco Rubio for the Republicans, perhaps, and Julian Castro for the Democrats.

In other words, pursuit of the Hispanic vote will fundamentally and irreversibly change the tenor and tone of the election. It would be ironic indeed if the legacy of America's first black president were to bequeath a country who elections were truly bilingual. That is where America is heading.