Dimitri Olympidis noticed two men walking along a road a couple of blocks from his Valparaiso, Ind., home. The men were bundled up and carrying large, heavy backpacks, heading west against a cold wind on a gloomy Wednesday evening.

“Where you headed?” asked Olympidis, who was driving home from work.

“California,” replied Trevor Stephens, 24, a U.S. Marines veteran.

Stephens explained that he and his friend from childhood, Matt Andersen, 24, are walking across the United States to raise money for the Purple Heart Foundation.

On March 1, the men left Lewes, Del., billed as “the first town in the first state.” They’re planning on ending their trip in San Francisco, hopefully by September.

Stephens and Andersen have been walking about 25 miles each day. They never know where they’ll sleep on any given night.

Olympidis invited the men to dinner at his home. He also offered them a ride, but they said they needed to get their miles in.

“My kids loved them,” Olympidis said the next day. They called the two strangers, “the cool guys.”

I caught up to them that afternoon as they neared the Illinois state line. They were planning to camp out in a forest preserve.

They never know for sure where they’ll sleep until it gets close to sundown, they said. They’ve been sleeping mostly outdoors, but every now and then they’ll stay in a hotel or motel to get cleaned up and to relax for a few hours.

Both men are from Council Bluffs, Iowa. Both are single with no children. Best friends since seventh grade, they met playing football at school.

“We both like traveling and we wanted to see the country,” Andersen said.

“It’s something not many people can say they have done, and we thought we should do it to support a good cause that we both believe in,” Stephens said. “We were looking into foundations that provided military veterans with assistance.”

One of Stephens’ staff sergeants, who’s a combat veteran, suggested the Purple Heart Foundation, chartered in 1957.

The foundation’s website states, “In combat, warriors count on their comrades to have their backs. Yet when they return home, when they face new and daunting challenges — emotional, medical, financial and more — who is there for them? Who has their back then? The answer is we do, providing counsel, a wide range of support, and unwavering advocacy. And a good measure of love.”

The men post updates of their trek on their Facebook page, “Matt and Trevor’s Walk Across America.” And on their Instagram page, “24 — and — much — more.”

“The people we’ve met along the way have been great,” Stephens said. “We’ve definitely been very blessed to meet the people we have. And we’re grateful for even the smallest contributions to our cause.”