Indiana: The state that could be pivotal for Donald Trump

The élites have a name for a state like Indiana: Flyover Country.

America's opinion formers only view this swathe of the heartland from 35,000 feet.

But not so fast. Today it is the centre of the political world, likely to decisively shape the Presidential race.

Indiana's slogan - "The Crossroads of America" - is true in a visceral political sense for the next few hours.

If Donald Trump wins here tonight, it is a near-fatal blow to his rivals.

Both Ted Cruz and John Kasich will be under pressure to drop out. The New York billionaire will declare the race is over.

He will pivot to the big enchilada - the showdown with Hillary Clinton that will consume America for the next six months.

In this state, you find all the ingredients for Trump's improbable success: Anger with Washington, alienation and poverty that fuel the sense that the American Dream is out of reach, and a hunger for revenge on the political Establishment.

So be amazed that Trump is now almost certainly the Republican nominee - it's the unlikeliest event that I can recall in American politics - but don't be surprised that Indiana gave him the final surge of momentum.

If only those élites had visited the state, not just flown over, they might have seen the ambush being prepared for them.