by James B. Stewart–

Here’s how President-elect Trump could unify a bitterly divided America, provide well-paying jobs to many of the millions of disaffected workers who voted for him, and lift the economy, stock market and tax rolls.

All he needs to do is what he presumably does best: build something.

And I don’t mean a few miles of asphalt or a paint job on a rusting bridge.

Build something awe-inspiring. Something Americans can be proud of. Something that will repay the investment many times over for generations to come.

Build the modern-day equivalent of the Golden Gate Bridge, the Lincoln Tunnel or the Timberline Lodge. Or even, given Mr. Trump’s passion for the sport, another Bethpage State Park Black Course — the first public golf course to host the prestigious United States Open.

All of these are Depression-era New Deal public works projects started under President Franklin D. Roosevelt that are still in use.

Can anyone name even one infrastructure project from President Obama’s $800 billion American Recovery and Reinvestment Act? I didn’t think so.

In fairness to Mr. Obama, Republicans in Congress bitterly opposed his public works spending plans, and he lamented there were too few “shovel ready” projects.

That didn’t stop F.D.R. His Public Works Administration and Works Progress Administration, using combinations of public and private money, solicited proposals from states and cities, hired millions of workers and eventually built 78,000 bridges, 650,000 miles of roads, 700 miles of airport runways, 13,000 playgrounds and 125,000 military and civilian buildings, including more than 40,000 schools — in most cases to high standards of quality and design.

The federal government built the La Guardia, Ronald Reagan Washington National and Los Angeles International airports, the Upper Mississippi locks and dams, the Bonneville power project on the Columbia River, the Robert F. Kennedy Bridge in New York, and the Florida Keys Overseas Highway. Most are still in use today. To a large degree, this is the infrastructure that made America great, to borrow Mr. Trump’s catchphrase.

What Roosevelt accomplished “is astounding,” said Scott Myers-Lipton, a sociology professor at San Jose State University and author of the books “Rebuild America: Solving the Economic Crisis Through Civic Works” and “Ending Extreme Inequality.”

But it’s not so much the numbers people remember today. “Most people just know there was an alphabet soup of organizations,” he said. “What they see and remember are the landmarks: the Bay Bridge, Reagan National Airport or the baseball stadium in San Jose. We’re living on that legacy today.”

Repealing Obamacare, lowering taxes for businesses and mostly wealthy people, overhauling the immigration system and privatizing Medicare — what congressional Republicans have cited as their top legislative priorities — would be divisive in a nation bitterly split along partisan and geographic lines. But nearly everyone agrees that America has grossly neglected its infrastructure even as the rest of the world, notably China, has raced ahead.

“Our airports are like from a third-world country,” Mr. Trump said at Hofstra University during the first presidential debate. “You land at La Guardia, you land at Kennedy, you land at LAX, you land at Newark, and you come in from Dubai and Qatar and you see these incredible — you come in from China, you see these incredible airports, and you land — we’ve become a third-world country.”

Who could disagree? Hillary Clinton also called for a big increase in infrastructure spending.

“The single best thing the federal government can do to promote economic growth is to repair and build the transportation network, the highways, railroads and airports,” said Roger Noll, an emeritus professor of economics at Stanford and a senior fellow at the Stanford Institute for Economic Policy Research. “It’s been neglected for 30 years.”

Last year, Dan McNichol, author of the book “The Roads That Built America,” a history of the Interstate highway system, and a White House adviser on transportation issues for President George H. W. Bush, navigated the country in a 1949 Hudson Commodore on a mission to investigate the state of America’s infrastructure.

“I was trying to see if this was really a crisis or a media sensation,” he told me this week from California, where he’s working on the state’s high-speed rail project. “I found out it’s pretty dire in terms of total infrastructure. For a nation that leads the world in global trade, our systems are failing.

Video How can President-elect Donald Trump unify America and provide jobs? Build something awe-inspiring, says James Stewart of The New York Times.

Mr. Trump has pledged $1 trillion over 10 years, but no one I spoke to thought that was enough. Doubling that would be more realistic, Mr. McNichol said. And Mr. Trump’s campaign proposal was limited to infrastructure projects that could pay for themselves out of user fees, which seems like a shortsighted approach. Most economists say the best way to finance a big public works program, particularly given today’s low interest rates, would be for the government to borrow most of the money from investors.

Pulling off something on the scale of the Depression-era public works programs would be no small feat. Recent federal infrastructure efforts, including reconstruction after Hurricanes Katrina and Sandy, as well as the Obama stimulus program, hardly inspire confidence.

Alan Brinkley, a professor of history at Columbia, said he doubted Mr. Trump could replicate Roosevelt’s achievements. “Roosevelt had a coherent mission, if not always a consistent way to address the Depression and the economic crisis,” Mr. Brinkley said. “He was eclectic in his approach because he was pragmatic.”

Even more important, “Roosevelt was informed, surrounded himself with informed people, and was prepared on Day 1 to begin. I’m not sure that Trump’s policies go beyond his electioneering slogans,” Mr. Brinkley said. “I’m afraid a new P.W.A.,” he added, referring to the Public Works Administration, “will stand for Promises Without Actions.”

But in the spirit of magnanimity, let’s give Mr. Trump the benefit of the doubt, as Mr. Obama has suggested. He’ll need his own versions of Harold L. Ickes, Roosevelt’s interior secretary, who ran the P.W.A., and his close adviser Harry L. Hopkins, who ran the W.P.A.

Mr. Trump will also need to be hands-on. Roosevelt asked states and cities for proposals, but he made nearly all the final decisions himself. “F.D.R. was a fanatic about infrastructure, roads, planning,” Mr. McNichol said. “As a commissioner in New York, he helped lay out the Taconic Parkway. He even helped design the picnic tables.”

So where should President Trump start?

For a sense of what might be possible, I asked Mr. McNichol to pretend he had just been tapped as Mr. Trump’s new infrastructure czar and to come up with a list of his top 10 infrastructure projects, balanced between red and blue states. Most are shovel-ready, or close to it. Here’s what he suggested, along with estimated costs:

Hudson River Rail Tunnel
Cost: $23.9 billion
The Northeast Corridor desperately needs another rail link connecting Manhattan and northern New Jersey. The current over crowded tunnel is over 100 years old and was severely damaged by Hurricane Sandy.

California High-Speed Rail
Cost: $65 billion
America’s first modern high-speed rail project would connect San Francisco and Los Angeles, about 400 miles apart, in under three hours.

The Gordie Howe International Bridge
Cost: $2.1 billion

Project Clean Lake
Cost: $3 billion
Seven new sewage and water tunnels would rescue Cleveland’s antiquated lines, which are overwhelmed by even moderate rainfall and feed contaminated water into Lake Erie. Picture pristine beaches and fishing, swimming and kayaking along a rejuvenated North Coast.

Northeast Corridor Maglev
Cost: $100 billion
Traveling at 300 miles per hour on a cushion of air, magnetically levitated trains could cut the commute from New York to Washington to an hour and render the painfully slow Acela obsolete.

Miami Sea Wall
Cost: $20 billion
Miami is one of the cities most vulnerable to rising sea levels and ocean surges. If the Atlantic Ocean rises just five feet, 96 percent of Miami Beach will be submerged. A system of levees, sea walls and storm surge protectors like the Maeslantkering in Rotterdam, the Netherlands — giant sea doors that open and close automatically to protect the harbor — could be both attractive and effective. Miami could be a prototype for other endangered American coastal cities and ports, including Boston; Charleston, S.C.; Galveston, Tex.; Savannah, Ga.; and New Orleans.

Denver I-70 East:
Cost: $1.17 billion
Denver is trying to put a section of Interstate 70 underground to reconnect the city’s urban fabric and use four acres of the reclaimed space for parks, bike paths and walks, and farmers’ markets. The green space could be much larger, further reducing pollution.

Maryland Purple Line
Cost: $5.6 billion
The Washington metro area suffers from some of the worst traffic congestion in the country. Maryland wants to build more than 16 miles of light rail to link its suburbs to Washington’s existing Metro system (which needs extensive repairs) and Amtrak. Supporters say it would remove 17,000 cars each day from area roads.

South Carolina Dams
Cost: $685 million
After a single heavy rain in 2015 breached more than 50 dams and caused widespread flooding, the Army Corps of Engineers assessed over 600 dams in South Carolina as either “high” or “significant” hazards. A single large project could modernize the state’s system of dams and water control.

Texas Bullet Train
Cost: $10 billion
Even without a federal program, Texans are actively looking for private investors for a high-speed rail link between Dallas-Fort Worth and Houston. Passengers would make the 240-mile, one-stop trip in 90 minutes. If successful, the line could be extended to San Antonio and Austin, covering the so-called Texaplex, which includes 75 percent of the state’s population and is home to 52 Fortune 500 companies.

The right public works projects, said Mr. Myers-Lipton of San Jose State, would “address the public anger that elected Trump, which is that the regular folks aren’t being taken care of.” During the Depression, “the government built beautiful hotels and golf courses and parks. The vision was, what’s usually for the elite should be for everybody. That’s the power of public works.”

Correction: November 19, 2016

The Common Sense column on Friday, about major public works projects that President-elect Donald J. Trump might consider, erroneously included one project among those started under the New Deal. While the Hoover Dam became part of the Depression-era public works undertaking, it was not started under President Franklin D. Roosevelt. It was planned, and site preparation had begun, before the New Deal.