America's white working class is shrinking, signalling a decrease in the size of Trump's most loyal fan base and marking the beginning of a slow decline until it becomes a minority.

According to research by the St Louis Federal Reserve, the percentage of white people in the US without a college education - which is how they categorize 'working class' - has dropped to 40 for the first time since 1975.

The reason for the decline is that a growing number of Americans are seeking out college educations and that some of the leading causes of death - suicide, alcoholism and opioid overdoses - are hitting the working class hardest.

A graph represents the decline of the white working class since 1975 from 70 percent of the country's entire population to 40 percent. By contrast, the minority working class is rising steadily as is the minority middle class

Birth rates are also slowing down in the group, leading to a 2.6 percent decrease across the country. In 2018, it hit its smallest at 87.1million people.

Though it is still the largest group, the researchers said white working class people will become a minority in 2034.

It is unclear which group will then overtake them.

White working class voters made up nearly 66 percent of Trump's base, according to 2016 exit polls, compared to Clinton's 29 percent. Earlier research suggested an even higher percentage of 70 percent.

Trump also won the majority of college-educated white votes but it was by a smaller margin, 48 percent over Clinton's 45 percent.

The researchers in St Louis found that while the number of non-educated white US citizens was decreasing, whites with a college degree were growing as a demographic as were working class black and Hispanic people.

Which will become the largest group remains to be seen but the fastest growing in most parts of the country is the non-white working class.

The research forecasts a socio-economic scenario that will playout long after Trump leaves office.

The researchers detailed where the white working class remained a majority (the Midwest) and where it is shrinking fastest (the Northeast). It has been overtaken in Western states

His last potential year as the president, if he wins the 2020 election, is 2024.

The researchers did not include any reference of politics in their essay, The Bigger They Are, The Harder They Fall: The Decline of the White Working Class.

The place where the white working class retains a comfortable majority is in the Midwest, where Trump is focusing his re-election campaign.

There, it makes up more than 50 percent of the population.

The next most populous group is the white middle class.

Elsewhere, the Hispanic or black working class is the fastest growing.

In Western states, that group took over working class whites as the largest and now makes up just over 30 percent of the population.