Let there be no doubt. US President Donald Trump is a mercurial, inept, me-first racist. In recent weeks, Trump has thrown in with Charlottesville's white supremacists and pardoned known anti-immigrant xenophobe Joe Arpaio. Trump has pursued an agenda of rescinding more and more of President Barack Obama's executive orders, including the Deferred Action for Childhood Arrivals (DACA), potentially leading to the deportation of undocumented immigrants who were children when they came to the US.

Trump's behaviour isn't unprecedented. His racist, incompetent, and callously narcissistic performance as president shares similarities with that of Andrew Jackson, Andrew Johnson, James Buchanan, Woodrow Wilson, and Richard Nixon. And although he continues to follow the lead of some of America's most racist and inept presidents, he continues to retain many of his supporters.

Millions of supposedly non-racist Americans - people who say they wouldn't align themselves with Neo-Nazis - continue to support Trump. Why?

Subconscious hatred or fear alone cannot fully explain why they tacitly support the Trump administration's racist and xenophobic policies, and Trump's racist and xenophobic words and deeds along with them.

The answer to this question lies in understanding the power of racial advantage and narcissistic self-gratification, the combination of which has made the Trump presidency possible. All that power is embodied in the reality of segregation in the US. Its diffusion in all aspects of American culture and life reinforces the idea of white superiority over Americans of colour and of America as a perpetually great and righteous nation, even as it isolates whole social and racial groups of Americans.

Racial and social segregation and the dominant white narrative

Residential segregation is the root cause of all other forms of segregation in the United States. Its immediate effect is that white children tend to go to school isolated from interaction with children of colour. As education expert Diane Ravitch wrote in her 2013 bestseller Reign of Error, "Today, racial segregation remains a pervasive fact of life for millions of black [and equally impoverished Hispanic] children, primarily as a result of residential segregation." Working-class and poor whites are residentially segregated not only from all social classes of Americans of colour, but also from affluent whites.

At the same time, white children tend to be almost exclusively taught by white teachers. Currently, nearly five out of six teachers in the US (82 percent) are white, and the majority of teachers of colour teach in school districts where students of colour are predominant.

Receiving homogenised education favouring a single narrative, many white Americans unsurprisingly are primed to agree with a president who consistently says they need to "take their country back" from Muslim 'terrorists' and Mexican 'rapists'.

But segregation goes even deeper than residential neighbourhoods and school district demographics. Knowledge and cultural segregation are equally damaging. It means most teachers consistently teach from a "hidden curriculum", one that accentuates the ideas, actions, and perspectives of whites over those of any other group. The "worldviews of those with privileged positions are taken as the only reality," educator Lisa Delpit wrote in Other People's Children (1995).

For students of colour, this means public education serves more as a prison and less as a level playing field. For white students, this cultural segregation and knowledge exclusion makes for an appalling ignorance of the full American experience - with its cultural richness and racial diversity - reinforces racial stereotypes and strengthens the inability to critically interrogate the surrounding world.

And despite the overwhelming privilege the white narrative enjoys in American schools, there are still attempts to extend its domination and subvert initiatives to teach diverse points of view. One such example is the state of Arizona's ban on ethnic studies which led to a school district dismantling a Mexican American studies programme. US federal district court judge A Wallace Tashima ruled the Arizona ban was unconstitutional, stating that both "enactment and enforcement were motivated by racial animus".

Receiving homogenised education favouring a single narrative, many white Americans unsurprisingly are primed to agree with a president who consistently says they need to "take their country back" from Muslim "terrorists" and Mexican "rapists". It is much easier for them to enthusiastically endorse an anti-Mexican Islamophobe when their life experiences limit them to a whites-first, whites-only, and whites-everywhere world.

Political exclusion

America's political parties have promoted of political segregation and exclusion. A favourite approach has been gerrymandering: the purposeful redrawing of voting district borders in order to ensure the domination of certain votes and the exclusion of others. The more popular method these days, though, is voter suppression: implementing policies which discourage or prevent people from voting.

This strategy, of course, aims at excluding mostly younger voters and voters of colour from political participation altogether. Voter suppression is a clear signal to the country that white and affluent voters are the ones who matter the most. It is no accident that the Republican Party has been the prime mover in these efforts in recent decades.

It is also not surprising that segregation and exclusion are something Trump knows well. After all, he grew up in affluent, lily-white Jamaica Estates in Queens, New York in the 1950s, and he worked for his father in the 1970s. The US Justice Department sued the Trumps in 1973 for housing segregation and exclusion against black and Puerto Rican applicants, a case the department successfully settled in 1975.

The perceived benefits of racial segregation and exclusion may be mostly symbolic and psychological, but for so many poor and working-class whites, the idea that the US is their country and the belief that the US is a great nation are very much linked. For they think that without them, the US would simply fall apart.

The irony is that Trump's presidential actions have shown that he is quite eager to exclude most of his white supporters from the benefits of social class mobility: by dismantling pathways to affordable housing, defunding public schools and defanging student loan borrower protections, and refusing to support green jobs.

There's no guarantee that less segregation and exclusion will prevent another Trump from becoming president in the future. But maybe it would keep millions of Americans from being so naive as to believe that a racial segregationist and social-class exclusionist like Trump would look out for their best interest.

Donald Earl Collins is an associate professor of history at University of Maryland University College. He is also the author of Fear of a "Black" America: Multiculturalism and the African American Experience (2004).

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.