Related Content The Oldest Structure on the National Mall Is on the Move

Update, January 26, 2017: Due to the massive crowds that visited the National Mall last week for President Trump's inauguration and the Women's March on Washington, The Trust for the National Mall is raising private donations to support restoration efforts to the Mall. More information can be found here

The National Mall in Washington, D.C., is one of the preeminent parks in the United States. It’s bordered by some of the country’s most revered museums and monuments, and it has witnessed some of America's brightest and darkest moments. But as tens of thousands of people swarm the nation’s capital for the presidential inauguration this Friday, the National Park Service is warning people to stay off its lawn.

Grass might seem like an easy thing to grow, but when it comes to lawns as trafficked as the National Mall, getting acres of the green blades to grow is harder than it seems. While the iconic park has hosted every presidential inauguration since it was built in the early 1900s, the record-breaking crowds that showed up to celebrate President Barack Obama’s first inauguration in 2009 had the unfortunate side effect of trampling the mile-long lawn into the dust, Sarah Laskow reports for Atlas Obscura.

“Everyone has a vision of the National Mall they see from a helicopter, and everything looks wonderful,” Teresa Durkin, senior project director of the Trust for the National Mall, tells Adrian Higgins for The Washington Post. “It’s not until you get down and walk around and see the impact of the sheer use — 3,000 permitted events, sometimes up to 33 million visitors per year.”

To be fair, the National Mall had been steadily deteriorating for at least 30 years, as tens of thousands of visitors trampled its manicured grass into the ground as they traversed from monument to museum. But the 1.8 million people who showed up for Obama’s inauguration did it in – by the time he was sworn in and the parties had died down, the National Mall was more dirt than a grass, and there was nothing that could be done to revitalize it aside from a soup-to-nuts makeover, Higgins reports.

“Grass is something that’s taken for granted,” Michael Stachowicz, the turf specialist in charge of the National Mall tells Laskow. “People can grow it in their yard and it’s fine. But I don’t have 30,000 people a day going over my lawn.”

Since 2009, the National Park Service has put $40 million into rejuvenating the National Mall. Over the last eight years, much of the park has been off-limits to the public as Stachowicz and his colleague painstakingly laid down new turf and reseeded the lawn to get it back to its pristine state. This time, however, the lawn-keepers have decades of grass-growing knowledge to turn to: Stachowicz seeded it with the right kinds of plants, made sure the soil composition is just right and that the Mall is now properly irrigated to keep it looking as fresh as it does in photographs, Laskow reports.

Timing is a funny thing, though. The National Park Service announced that the project was finally complete back in September – meaning they now had a few months before hordes of people descended on the Mall for another inauguration. In order to protect the fresh turf, the agency has brought in special, translucent panels that will allow people to walk on the Mall without crushing the grass. As Laskow writes, these panels will not only allow light to reach the refreshed lawn, but have many small cells that will keep the grass from being crushed beneath them. Since these little boxes act like tiny greenhouses, the new grass might even look a little healthier once the crowds have left, as they will have gotten extra shelter from the harsh winter elements.