Melissa McCarthy, 68, on the summit of Loveland Pass in the Rocky Mountains of Colorado, in July 2015. (Courtesy of Melissa McCarthy)

Melissa McCarthy was frustrated. She was disgruntled about the state of the country’s politics and irked by what she saw as people’s disregard for the environment.

So she decided to walk it out — across the entirety of the United States over the course of more than two years.

“My initial kind of frustration was in the realm of, ‘I don’t know what to do. I just have to go out and walk,’ and to express my frustration and devotion to the Earth,” said McCarthy, 68, who is from San Francisco and was ordained as a Zen Buddhist priest in 1998.

“It feels to me like a personal pilgrimage, as well as for the environment,” she said. “It’s an opportunity to pay respect to the earth.”

It was also an opportunity to connect with her fellow Americans. Watching the news from a television screen, she said, one gets a very skewed picture of the nation.

“You begin to wonder, who the hell are we?” she said. “I just wanted to find out, who are we Americans anyway?”

With not much more than a two-wheeled walking trailer strapped to her waist and packed with a tent, some clothes, food, water, toiletries and a book (“Sometimes I allow myself to have two”), McCarthy set off in March 2015 from Avila Beach, Calif., to walk across the United States.

Flying from her trailer also is a climate flag, striped white, yellow, blue, and green to represent the sun, ozone, water, and Earth.

Last week, McCarthy arrived in Washington, D.C., having spent several days walking along the Chesapeake & Ohio Canal. If all goes according to plan, she will soon complete her journey by dipping her feet into the Atlantic Ocean at Rehoboth Beach, Del.

The solo pilgrimage has not been without setbacks.

About five months into her expedition, in Fort Morgan, Colo., McCarthy was diagnosed with rhabdomyolysis, a rare but dangerous condition linked with extreme physical exertion, in which muscle breaks down and releases a protein into the bloodstream. She took a train home to recover and resumed the next spring from where she left off. She made it to Crown Point, Ind., when she tripped on a piece of wire and fractured her jaw. Undeterred, she flew home, rested up and resumed her journey from Crown Point late in April.

McCarthy poses for a portrait in Washington, D.C. She plans to reach her final destination in about a week. (Mary Hui/The Washington Post)

On a recent afternoon, McCarthy scrolled through photos on her iPhone, telling stories of the many different people she has met on the road.

Most humbling, she said, has been the poverty she has encountered — and people’s generosity despite it.

There was a couple in Ohio, outside whose trailer she pitched her tent one night. They didn’t have much, McCarthy said, but nonetheless were “happy enough to invite me to their yard and share their fish sandwiches with me for dinner.”

There was a family in West Virginia where no one except for the youngest boy had any teeth left.

There was a man in Utah who pulled up in his pickup as she sat on the side of the road, admiring the canyon. When she told him that she was walking in honor of the environment, he said he didn’t much believe in climate change —  but that he would follow news about it now that he had spoken with her.

“He thought I was walking my talk,” she said.

McCarthy recites Buddhist chants on her walks, and sees her pilgrimage as a spiritual journey, as well as a way to stand up for her values. But she is also steadfastly humble about her pursuit.

“People make this walk to be so virtuous, but I don’t feel virtuous,” she said. “I feel like I don’t have a choice…it doesn’t feel like a big deal compared to the degree of danger we’re in as humanity.”

More than anything, she feels compelled to walk by a sense of urgency.

“The time is over when we can be idle because we don’t think we can make a difference,” she said. “We have to stand up because it’s fatal if we don’t.”

McCarthy expects to arrive at her final destination in about a week. But with the troubled state that the country is in, she said, she may well have to embark on another pilgrimage soon.

“I don’t think I can stop walking,” she said.