It’s no secret that many top-flight business leaders have been visiting the White House over the past couple of months.

But the biggest meeting of all took place on March 9, when a cadre of businesspeople, real estate developers, and environmentalists visited President Trump to discuss his plan to repair the nation’s crumbling infrastructure. The guests included General Atlantic CEO William E. Ford, McKinsey & Co. partner Tyler Duvall, and Nature Conservancy Managing Director Lynn Scarlett.

Most notably, the guest roster included Elon Musk, the CEO of Tesla, SpaceX, and the Boring Company.

Trump has pledged to rebuild America’s infrastructure. In February, he told Congress, “To launch our national rebuilding, I will be asking Congress to approve legislation that produces a $1 trillion investment in infrastructure of the United States—financed through both public and private capital—creating millions of new jobs.”

But even that may not be enough. According to an article in The Mercury News, the American Society of Civil Engineers estimates that the U.S. needs $3.6 trillion in infrastructure investment over the next three years.

In fact, the organization just gave America a “D+” on its infrastructure. Airports, for example, face a $42 billion funding gap in the next 10 years and need serious basic safety like air traffic control systems.

There are about 56,000 structurally deficient bridges in the U.S, and more than 200,000 of the nation’s 614,387 bridges are more than 50 years old. In fact, the Pfeiffer Canyon Bridge on Highway 1 in Big Sur, California, recently crumbled beyond repair and has been condemned due to storm damage, cutting off 450 residents of the community from the rest of the state.

Other essential services like water treatment and the power grid have serious problems that need immediate attention as well, says the ASCE’s report.

White House spokesman Sean Spicer recently said, “Infrastructure used to be a point of American pride, but now an overbearing, ineffective regulatory system can keep projects in limbo for years. The government has wasted too much of the taxpayers’ money on inefficient and misguided projects.”

Not much is known about exactly what Musk and the business leaders discussed with President Trump, but many guess it had to do with the importance of building public-private partnerships to help rebuild America’s infrastructure and developing a plan to do so. It is, however, known that Musk cares enough about infrastructure to put some of his vast resources toward building a tunnel under Los Angeles in hopes of helping ease the city’s infamous traffic congestion.

Although public tunneling projects often run into engineering snafus and have, to this point, gone over budget and taken more time than planned (think of Boston’s Big Dig, New York’s Second Avenue Subway, and Seattle’s current efforts to replace the structurally deficient Alaskan Way Viaduct with a tunnel under the city), they could offer a reprieve from traffic problems if they are successfully completed. Perhaps Musk’s plans and engineering will help update tunneling technology.

“We’re going to figure out what it takes to improve tunneling speed by, I think, somewhere between 500 and 1,000 percent,” Musk said during a recent hyperloop design competition at SpaceX. But at this point it’s all theoretical, he warned.

Innovative ideas like Musk’s tunnel under LA and other ideas from the private sector could definitely go far to improve the United States’ roads, dams, railways, bridges, and airports, among other things.

We hope that President Trump and Congress will join that public-private partnership to rebuild our infrastructure with enthusiasm and support. Judging by the recent meeting of the minds at the White House, it looks like that is going to happen.