It’s the great unanswered question of the presidential campaign: Just how can America actually create jobs? President Barack Obama and Mitt Romney are ducking the specifics, tearing each other down and offering little hope to the 15 percent of Americans without enough work.

The rhetoric of the campaign and the coverage by political journalists don’t deal with the subject except in the context of the back-and-forth insults that have marked this contest. For example, last month Obama, talking about why the rich should pay their fair share of taxes, stated the obvious: “If you were successful, somebody along the line gave you some help. … The Internet didn’t get invented on its own. Government research created the Internet … when we succeed, we succeed because of our individual initiative, but also because we do things together.”

Any successful entrepreneur with a restaurant or retail operation on an interstate highway would probably agree. But Romney picked it up as more evidence of Obama’s rejection of the national entrepreneurial spirit. “It shows how out of touch he is with the character of America,” Romney said. Obama isn’t out of touch with the American character. But the negativity of his unrelenting attacks against Romney puts him out of touch with the main American need — specific ways of lowering the unemployment rate.

Away from the campaign trail, in the real world, life is different and the entrepreneurial spirit exists to a great extent because workers, business people and governments work together on the complex and frustrating task of actually creating jobs. The New York Times reported Sunday how state government, using financial incentives and salesmanship, with a little help from Congress, persuaded Nissan to build cars in Tennessee. Now, the Times said, Tennessee has more than 60,000 jobs related to automobile and parts production. The state unemployment rate, once above the national average, is now slightly below it.

In June, a small city north of Los Angeles, Lancaster, with the intense effort of its development director, Vern Lawson, and the rest of the municipal government successfully persuaded a 300-employee company to move to town. After the Obama-Romney exchange, I thought again of job creation and government agencies, which do it on a much larger scale. I looked at Los Angeles Harbor, which has interested me as long as I have lived in the city.

It started with a scandal. Before I moved to Los Angeles, the president of the Board of Harbor Commissioners was found dead in 20 feet of water, as a grand jury investigated alleged conflicts of interest. So suspicious was his death that years later, when Sam Yorty, who was then mayor and had appointed the commissioner, complained to me about one of my stories, I said, “Oh no, mayor, not the harbor.” He said nothing but gave me one of the darkest looks I’ve ever received.

Later, coverage of pollution brought me to the harbor to write about ships that poisoned the air in schools and homes in the poor neighborhoods around the port. At the time, the harbor was a symbol of a cruel and indifferent government.

Now it’s jobs. Lawsuits by neighborhood and environmental groups had forced the harbor to clean up air pollution and cleared the way for the construction of new docks that will create employment. Working with the adjoining Long Beach Harbor and local officials, the L.A. Harbor was involved in the construction of a high-speed freight rail line, the 20-mile-long Alameda Corridor, which links the harbors to the intercontinental rail network. All this has produced thousands of jobs, raising the question: What was Romney talking about?

At midmorning on a sunny summer weekday, I boarded a boat with several other guests for an update on the harbor. The sky was blue, although I knew air pollution in the entire Los Angeles area was high. The water was clean enough to see seals swim by.

We passed relics of the old manufacturing economy that pulled the United States out of the Great Depression and through World War II — the USS Iowa, a battleship commissioned in 1940; a World War II cargo ship built by the formerly unemployed; an abandoned shipyard. Taxpayers financed those projects and many more. The revived economy allowed the country to grow after the war, as did programs such as the GI Bill of Rights. Not all the veterans who benefited became great entrepreneurial, professional or political successes, but most moved into the middle class. Neither they nor those who reached the heights would have made it without government financing.

To put together today’s job-creating projects, Los Angeles city government had to navigate a morass of local politics in which terminal companies, unions and local property owners share power. It raised money from lease payments for the terminals, state funds and the Obama administration’s anti-recession stimulus program, and is using the money to build new roads and cargo container terminals. Cindy Miscikowski, president of the Board of Harbor Commissioners, which runs the port, said it adds up to a four-year construction program costing about $365 million a year. “That’s a million dollars a day with high-paying construction jobs,” she said. Along with that will be jobs on the new docks and in the warehouse and distribution centers reached by the Alameda Corridor line.

This is an example of the worth of government spending, financed by tax revenues, giving business the tools to build and to raise employment. Although improvement is slow and painful, it’s happening around the country thanks to men and women who understand that creating jobs is a cooperative business.

Despite Romney’s complacent views about the power of the entrepreneur, Apple — even with the genius of Steve Jobs — wouldn’t have become Apple without the government-created Internet.