(Scott Olson/Getty Images)

The rise of Donald Trump has put the focus on one particular demographic: men. In a provocative post entitled “What the hell is going on?” the economist Tyler Cowen argued, “The contemporary world is not very well built for a large chunk of males.” Understanding the views of men, and particularly Trump’s base of white men, is key.

Of course, part of Trump’s appeal among white men has to do with their racial attitudes. But part of the story may also have to do with the economy — and especially the stagnant incomes of white men.

In the graph below, I plot the trend in inflation-adjusted median income, as reported by the Census Bureau, for white males, white females, black males and black females.

The census data starts in 1953. From then until 1967, the median income of white males increased substantially, while that of white women increased very little. Black men and women also saw substantial progress, but the greatest income gains belonged to white men.

But after 1967, white male median income, adjusted for inflation, has been virtually stagnant, while that of white females nearly doubled. Black female median incomes more than doubled. Black males saw some increase.

White men today are slightly worse off than in 1996. Meanwhile, even with the Great Recession and modest economic growth, white females, black males and black females have made modest progress, compared with 1996.

Any increases in white male incomes have mainly gone to the wealthy. This is why the average income among white men grew $4,000 between 1996 and 2014, even as the median income was stagnant. (This gap would be even larger, but the census income figures do not take into account capital gains.) Indeed, the Forbes 400 list, repopulated by tech innovators and hedge fund operators, is increasingly white men.

Needless to say, the income gains among women and minorities are important. Nevertheless, income stagnation among white men provides an economic basis for Trump’s appeal to middle-class white males, even as many high-income Republicans disdain Trump’s populism.

Even without Trump in the race, one of the more notable trends of the past decades has been the movement of white men into the Republican Party. In fact, in our book “Polarized America,” Nolan McCarty, Keith Poole and I show that, in the 1950s, the gender gap in voting was actually reversed, with women, rather than men, more likely to favor the Republicans.

Why has the gender gap changed and white men relocated to the GOP? One possibility is a shift in the Democratic Party’s platform. The political scientist John Gerring has shown that the Democratic platform shifted away from general social-welfare programs (such as Social Security) to issues based on social identity. The shift occurred in 1972, about the time that white median income began to stagnate.

Gerring’s observation is confirmed by the 2016 Democratic platform. The platform has many economic references to women and people of color — such as equal pay, expanding Social Security for widows and women who exited the workforce to care for children or family, of housing foreclosures, of access to housing. The platform seeks to “nurture the next generation of scientists, engineers and entrepreneurs, especially women and people of color.” The platform mentions whites only in the context of their greater wealth, lower arrest rates and lower job losses.

In contrast, the Republican platform never refers explicitly to Latinos or people of color, and refers to African Americans or Hispanics only once and then in the context of seeking to reduce federal expenditures on primary and secondary education. It refers to women only in the contexts of the military and the pro-life position on abortion. In short, the Democratic platform takes an implicitly negative position on the relative economic fortunes of white males, while the Republican platform takes a neutral one.

Of course, these shifts in the Democratic platform and coalition may give them long-term electoral advantages, particularly as the country becomes more ethnically diverse. And Trump’s candidacy may even help the Democrats among some white voters, especially those with college educations.

Nevertheless, the consequence of these shifts in party platforms — combined with trends in median income — may be a base of white men that is loyally Republican and increasingly attracted to populist appeals such as Trump’s.

Howard Rosenthal is professor of politics at New York University and Roger Williams Straus professor of social sciences, emeritus, at Princeton University.