Kerry Allen doesn’t have a car, so she will commute to her Capitol Hill job many mornings with a pair of running shoes, and other days she will squeeze in a few more miles circling the National Mall at lunchtime. Kelly Calway has school drop-off most mornings, followed by a full workday. So she usually waits until after bedtime to hop on a treadmill and log her miles. Kieran O’Connor also has two kids at home, so he tries to find a block of time each weekend to sneak in a quality training run.

All three have qualified for Saturday’s U.S. Olympic marathon trials, perhaps the most unusual, accessible and democratic qualifying event for the Tokyo Summer Games. In many Olympic sports, only the best of the best — think of full-time athletes with shoe contracts and dedicated sports agents — reach this stage. The marathon trials provide a much bigger tent, allowing the nation’s top amateurs, including working parents and dedicated recreational runners, to run alongside the fastest long-distance runners in the country.

Roughly 700 runners are expected at the starting line in Atlanta on Saturday — 511 women and 260 men have qualified, though not all will run — but only a handful have a realistic shot at the precious few spots on the U.S. Olympic team. The top three male and female finishers will punch a ticket to Japan.

“Massive,” Tim Hutchings, NBC’s race analyst, calls the U.S. trials field. “That’s far more than you’ll ever get in any other discipline, whether it’s runs, jumps, throws, walks, whatever. I guess that’s pretty apt because road racing is probably the most popular mass participating sport in the world. … I love the democracy of Joe Blow ordinary runner being able to line up next to superstars.”

Saturday’s race will feature Des Linden, the two-time Olympian and 2018 Boston Marathon champion, and Molly Huddle, the decorated distance runner. It will have Galen Rupp, who won the marathon bronze at the 2016 Games, and 45-year old Bernard Lagat, the ageless wonder who is somehow trying for his sixth Olympics. But it includes far more amateurs, runners without endorsement deals who squeeze training runs in between jobs and kids and life, which makes Saturday’s mass start unlike any other Olympic trials or qualifying event.

“You have people from all different walks of life,” O’Connor said. “It’s just a very diverse set of people, but it’s very much a community.”

For many, the toughest part is getting to the starting line. The process can span years, multiple races and several time zones. In July 2017, USA Track & Field announced its qualifying standards to gain entry into the Olympic trials, which gave any hopefuls less than 2½ years to hit their marks — 2 hours 19 minutes or faster for men, 2:45 for women.

“There’s a lot of stress that goes into qualifying,” said O’Connor, who will be competing in his second marathon trials Saturday. “But once you’re there, it’s like a victory lap. I know I’m not competing for a spot on the Olympic team, so the honor for me is being there, soaking it in and having the experience of competing against the best marathoners in the country.”

Deep talent pool makes U.S. unique

A total of 771 runners qualified for the trials, the most ever and 314 more than four years ago. Hutchings, a former long distance runner from Britain who competed in the 1984 Games, notes that most countries don’t have as deep of a talent pool.

“Here in the U.K., if we put on a trials race and we had similar criteria . . . we’d have 30 to 40 guys running and 20 to 30 women,” he said. “USA is a massive force, the No. 3 distance running country after Kenya and Ethiopia.”

But even in countries with loads of elite talent, a single, dedicated race to select an Olympic team is mostly unheard of. Each nation can choose its Olympians in any manner it wishes, provided the runners hit the international standards to qualify. Kenya and Ethiopia might have several runners technically eligible, but earning a spot in the Olympics is no simple matter, and many nations rely on a selection committee and arbitrary standards.

“None of those athletes have the foggiest idea of how they can actually get elected,” Hutchings said. “On a wing and prayer, go to two or three races, hope they get the sympathy and catch the eye of a selector and get picked for the team.”

Because only an elite handful in Atlanta on Saturday realistically have a shot at a top-three finish, the nature of the race is different from so many others. Calway will be running in her third marathon trials. Unlike some races, there’s no elbowing or icy stares at the starting line, she says, no jostling or cold shoulders at the finish. She calls the entire experience “profound.”

“You’re running in pack of women, and everybody’s working together, this big group and so much encouragement,” she said. “Everybody’s at a level of understanding. Not everybody’s going to make the Olympic team, so there’s a little less pressure than some other races.”

Calway, 35, has been in the sport long enough to know that satisfaction doesn’t solely come from her place on the results sheet. A major in the Army, she has had two combat deployments, and her husband has had three, which has left her alone with the family for long stretches. Somehow she always made time for running.

“You don’t do that without loving it,” she said. “I know personally for me, I have two daughters now, and I want to show them that Mommy is still going for a dream and committed to something.”

Motivations are as varied as the runners

While the top pros might be disappointed with a fourth-place finish Saturday, Allen will try to not even look at her watch or fret over her pace. Like many others in the field, the race isn’t a steppingstone as much as it is a culmination.

Allen, 30, began running in middle school. There were some struggles in high school but she still earned a spot on Duke’s track team. Injuries dampened her enthusiasm, and Allen decided to focus on her studies.

“I did not have a good relationship with running at that point,” she said, “which I think was mostly self-imposed, putting a lot of pressure on myself, like, ‘Why can’t I get faster?’ ”

She studied public policy and later settled in Washington, taking on a roommate who was a recreational runner, who inspired Allen to lace up her shoes again. Running became a respite of sorts. Allen is now a senior policy adviser for Sen. Mazie Hirono (D-Hawaii), focused on health care and veterans issues. Running to or from the Hart Senate Office Building each day provides rare quiet time.

“For me, it’s the one time of day that I’m guaranteed to not have other distractions,” she said.

Her job can feel all-consuming at times, but the Olympic trials had been an important goal. Allen had three straight rough marathon attempts when she entered the Twin Cities Marathon in October. She needed a personal best to qualify for the trials, so she was more focused on a strong showing and healthy finish. At the halfway mark, though, she knew the trials’ standard time was in sight.

“Every step I took, I was more and more confident that I was going to make it,” she said.

At the finish line, she burst into tears. Her time — 2:41:33 — was 10 minutes faster than she had ever finished and guaranteed her a spot in Atlanta.

“It’s like all the years of hard work and the bad marathons and even bad experiences going back to high school, it all came out,” she said. “A volunteer saw me and was, like, ‘Do you need medical help?’ I told her, ‘No, I’m just really, really happy.’ ”

That finish ensured her place — not in Tokyo but in something that feels just as satisfying.

“There’s literally no chance that I qualify for the Olympics,” she said of Saturday’s race. “Making it to the trials is my Olympics.”

Read more from Post Sports: