Whatever you think of Donald Trump, his presidential campaign has forced American elites, both liberal and conservative, to confront the growing class divide that is fracturing this nation. This isn't the rather porous divide between the 1 percent and 99 percent that alarms progressives such as Bernie Sanders.

Instead, it is the increasingly steep barrier between the 30 percent of working-age Americans who have college degrees and knowledge-based occupations and the 70 percent who do not have college degrees and, if they have jobs at all, mostly have labor-based occupations. Sociologists traditionally call the former group middle class and the latter working class.

Fifty years ago, the distinction between middle class and working class was disappearing into a "middle-income" group as working-class incomes were a substantial fraction of, and in some places equal to, middle-class incomes. Cultural divides were falling as working-class families lived in the same neighborhoods, drove similar cars, watched similar television shows, and ate similar foods as middle-class families.

This happened because the United States after World War II was the industrial powerhouse of the world, while other industrial nations were rebuilding. By the 1970s, however, those other nations were exporting cars, televisions and other consumer goods to the United States. For the middle class, free trade meant lower-cost consumer goods; for the working class, it meant fewer and lower-paying jobs.

While trade has been central to Trump's campaign, it is not the only reason for the growing divide between the classes. In addition, the middle class has worked hard to design a society that works for it, but not for the working class.

For example, many states and cities have passed laws and rules making housing artificially expensive. They say they want to attract the "creative class" to their cities and regions. According to Richard Florida, who coined the term, the creative class are the 30 percent of people who are knowledge workers — in other words, the middle class.

Though Florida's books might not have sold as well if he had used more traditional terms, the converse of cities saying they want to attract the creative class is that they want to discourage the working class. They do so by making housing less affordable, and regions such as Silicon Valley and Boulder, Colo., have high average incomes not because they have attracted high-income people but because their unaffordable housing has pushed low-income people out.

Transportation policy is another way the middle class discourages the working class. About half the urban areas in America have decided that it is too expensive to build their way out of congestion, so they do little to increase highway capacities. Middle-class workers can get around congestion by working at home or on flex-time hours, but most working-class employees don't have those options.

Fifty years ago, children of working-class families could enter the middle class by going to state colleges and universities, where tuitions were low and even free for in-state residents in California. Today, public university tuition has become a huge barrier for working-class children, greatly reducing America's social mobility.

Another traditional path out of the working class was to start a small business. To practice law, all Abraham Lincoln needed was a document from an Illinois court certifying his good moral character. Today, hundreds of occupations have onerous licensing requirements, many of which include having a college degree, and small businesses face numerous other regulations.

All of these barriers have restored the cultural rift between middle and working classes that was disappearing in the 1950s and 1960s. Today, members of the two classes drive different kinds of cars, eat different foods and listen to different music. If you qualify as middle class, you probably don't count many working-class people among your friends.

To some extent, these class barriers have been inadvertent. But to a large degree they are deliberate, as elites view the working class with sympathy in theory but treat actual working-class people with contempt. Trump supporters are racists, they say, anti-gay, anti-choice and they certainly don't want them living in their communities, recreating in their resorts, or catering their weddings.

If Trump loses the election, it will be because he has limited his message to white working-class voters, when in fact black, Latino and other working-class minorities are harmed just as much by the barriers the middle class has built between them. No matter who wins the election, it is time to tear down these barriers and make America once again a land of opportunity.

Randal O'Toole (rot@cato.org) is a senior fellow with the Cato Institute and author of American Nightmare: How Government Undermines the Dream of Homeownership.  Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.