JOHNSON'S CORNER, Colo. –Sitting in the cab of his blue Volvo big rig, trucker Lee Robertson leafs through the sheaf of papers listing what's stacked inside the refrigerated trailer hooked up behind him.

"Eggs. Cream cheese. Vegetables. Chicken," he shouts over the rumble of engines from semi-trailers parked at this truck stop between Denver and Cheyenne. "Soy milk."

Robertson, 56, of Kansas City is hauling a load destined for small shops and convenience stores across the country. He's not alone.

Across the United States, the nation's 3.5 million professional truckers are working flat-out to keep stores and businesses stocked as consumers worry about riding out home quarantines prompted by the coronavirus outbreak and try to snap up enough toilet paper, rice, beans, tuna and other staples to get through this period of uncertainty.

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Many truckers said they aren't overly concerned about getting sick, although their jobs – which require touching shipments that could be contaminated, interacting with others, and going out in public at a time when many lawmakers are urging people to stay home – could put them at increased risk of contracting the virus.

Restrictions on which businesses can remain open have also made their jobs more difficult, forcing some truck drivers to cook for themselves in their trucks as restaurants across the nation shut down. In other cases, it has left them without a place to wash their hands or to park and sleep at night. Dozens of rest stops were closed in Pennsylvania, Texas, Nebraska and Michigan this week because of efforts to slow down the coronavirus outbreak.

A trim man with neatly trimmed hair and goatee reflecting the barber he was until 18 months ago, Robertson, along with many other truck drivers, now finds himself on the front lines of the nation's efforts to survive an outbreak that has forced tens of thousands of restaurants to close and emptied grocery store shelves nationwide.

"They told me that I'm essential personnel so don't even think about getting sick," Robertson says with a laugh.

He's proud to be helping out, he says, but he's also pleased with the pay and job security. Truckers can earn more than $90,000 a year, plus benefits, at a time when thousands of Americans have already lost their jobs because of coronavirus closures.

Truckers are tasked with moving a staggering amount of goods, ensuring Americans have their fill of grocery items, toiletries, online purchases and other goods: The industry hauls more than 10 billion tons of freight annually, which accounts for more than two-thirds of the total freight tonnage moved nationally. By contrast, rail transportation moves about 13% of the nation’s freight tonnage, according to the American Trucking Associations.

"I think people, quite frankly, take truck drivers for granted when things are normal," says Todd Jadin, vice president of talent development and associate relations for Green Bay, Wisconsin-based Schneider, which has 11,000 company drivers and 3,000 owner-operators. "The work they do every day is that much more important right now."

While consumers have begun to fret in recent days about shortages and suffer through home quarantines, trucking companies say they've seen no slowdown in supplies: factories and meat-packing plants are still running at full operation, and there's plenty of food, toilet paper and other supplies to go around. That means drivers, as always, are needed on the road.

"I like to challenge people," says T.J. O'Connor, COO of Kansas-based trucking and logistics company YRC Worldwide, which has 30,000 employees across North America. "Look around the room and show me something that wasn't on a truck at one time. We are the lifeblood of the economy. We are the lifeblood of the supply chain of North America."

Drivers say they're working hard to meet consumers' needs during the pandemic while also adhering to safety standards requiring adequate rest, just like pilots. In recognition of the crisis, federal officials have temporarily loosened rest requirements for truckers delivering essential supplies. Under the new rules, truckers who are delivering a load toward the end of their shift are allowed to make the delivery even if they're temporarily delayed in traffic, instead of having to immediately take a break.

Still, with institutions across the U.S. rapidly shutting down to stop the spread of the virus, some drivers say they are worried about the knock-on effect of schools closing, as well as warehouse workers being quarantined, industry experts said.

"If a school system closes down, our employees may not have child care," O'Connor says. "Or we have a driver go out there to make a pickup and there's a sign on the door that says one of the employees tested positive and they're closed. What do you do?"

As of Sunday morning, there were more than 345 deaths and over 27,000 confirmed COVID-19 cases in the United States. Worldwide, the death toll has topped 10,000, with more than 316,650 confirmed cases, according to the Johns Hopkins University data dashboard.

O'Connor said the situation remains manageable for truckers but worries what happens if things don't improve soon. He said there already has been an increase in the number of loads drivers can't deliver because some warehouses or delivery sites are closed from a lack of workers, and the goods must be stored somewhere so drivers can pick up their next assignment.

The American Trucking Associations has been in regular contact with the Trump administration about ensuring the smooth flow of goods across the country, said Bob Costello, the trade association's chief economist.

Trucking companies want to ensure drivers can at least temporarily maintain their licenses and certifications if state DMVs are closed, and to continue providing access to truck and rest stops nationally so drivers can rest, refresh and eat. While it might seem like a minor thing to people stuck at home, truckers who live and sleep in their rigs need access to showers and hot meals, too.

"These men and women are out working, and I'm sure they want to be home with their families just like the rest of us," Costello said. "They are out there working so we can get our stuff, and we need to make sure we treat them right. They deserve that."

Back at Johnson's Corner, truckers say one benefit of the coronavirus restrictions is the lighter traffic on the nation's roads.

A driver since 1991, Ron Applegate says he is proud of his work to keep the supply chains filled, even if it means he's having to make coffee and cook more in his cab since tens of thousands of restaurants have shut down. In the past few days, he has been to Texas and Nevada and Colorado, hauling hay and insulation and anything else his dispatcher tells him to pick up.

Like many truckers, he's blase about the risks from the coronavirus, in part because many long-haul truckers interact with so few people face to face: "If the good Lord wants me to get it, I'll get it."

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Right now, he's more worried about keeping to his schedule, taking his required rest breaks and delivering for customers.

"I haven't stopped since this all started," says Applegate, 57. "If the freight's there, it's got to move. If people are going to eat, the trucks are gonna move. If they need medical supplies, the trucks are gonna move. If we stop, the world stops."