One second.

That’s what separated Rachel Scott from an entry into the 2016 Boston Marathon. Shoes & Gear that her time proved heartbreakingly short of what she needed to be guaranteed a spot.

“It would have been easier to deal with if it had been 10 seconds,” said Scott, who was among the 4,562 people who met the marathon’s official qualifying standards but still lost out under the race’s current registration procedures. “But one second is nothing. There are so many places you can make up one second in a race.”

More than one in six runners who attempted to register for the 2016 running of the storied race were turned away when so many applied that only those at least 2:28 faster than their official qualifying times got in. That’s more than double the proportion of rejections that occurred last year.

Like many of the runners who missed the cut, Scott, 32, of Beaumont, Texas, has been trying for years to qualify for Boston. She beat 3:40, but only after the qualifying times were moved up to 3:35 for her age group. “I’ve always been, like, almost there,” she said. So when she finished the New York City Marathon last year two minutes and 27 seconds under that 3:35 goal—in her ninth try since 2004—“I felt pretty good.”

Then came the email telling her she was short. By one second.

Running Boston “has been my lifelong ambition, so it’s hard to say I’m done. But I’m also tired,” said Scott, a math teacher who had her fourth child last month. “It’s hard that there’s not a hard and fast number that you know you have to hit.”

Boston Marathon Finish Cutoff Time Is 5:30 p.m Boston Athletic Association said it’s gotten only a few phone calls or emails from disappointed applicants since the rejection notices went out. When it does, the best that representatives can do is explain the math. There is no appeals process.

Most of the reaction has come via social media—runners saying they were drowning their regret by binging on ice cream and cookies, for example, but most vowing to try again and offering encouragement to those who scored a number.

“We certainly know that there are people who are disappointed, and we take no joy in it whatsoever,” said Tom Grilk, executive director of the BAA.

For the 2015 running, applicants needed to be 1:02 faster than their official qualifying times to get into Boston, and in 2014, 1:38 faster.

“The interesting phenomenon in all of this is that for these runners, they’re really not right now competing against the BAA qualifying standard. They’re competing against all the other people who are out there running," Grilk said.

And while marathon times in general aren’t necessarily getting faster—last year marked the slowest average finishing times since 2005 (4:19:27 for men and 4:44:19 for women), according to the industry group Running USA—the number of marathon finishers is at an all-time high of more than half a million annually, compared to 353,000 in 2000. And a lot of them want to run Boston.

Rumblings that the official qualifying times wouldn’t be good enough began appearing when Health - Injuries.

“A week in advance, I started to worry,” said Daphne Matalene, 41 who has wanted to run Boston since she was a student at Wellesley College in the ’90s cheering runners on the course. She thought she was finally in when she posted a time in last year’s Chicago Marathon of nearly two minutes faster than her Boston qualifying requirement. “I crossed the finish line and started yelling. ‘I’m going to Boston! I’m going to Boston!’”

Matalene, a freelance writer and editor who lives in New York, relaxed and took a full year off from marathons. “I wouldn’t have done that if I’d known I needed to take another crack at it. I thought I had made it for a full year. I planned my whole life around it.”

Richard Sullivan, an electrical engineer from Dallas, also started worrying when blogs began to calculate the cutoff times, which were just higher than the nearly two-minute cushion he had scored at August’s Nebraska State Fair Marathon.

“I looked at the past four years of cutoff data and I kind of thought, well, 98 seconds was the previous cutoff, so I thought that should put me in safe territory,” said Sullivan, who is 35. “I felt really, really good about my chances, that I was going to get in.”

Then, he said,  “I started obsessively checking every website for projected cutoffs. Anybody who had an opinion on it I was trying to get an idea what it was going to be. I saw the announcement about the record number of registrants in week one.” And by the time he got his rejection notice, “I was already trying to begin the grief process. I was still really disappointed, but somewhat prepared.”

Retired teacher Ken MacKenzie, of Amherst, Nova Scotia, also thought he was in. At 57, he had slowly improved his time until he finished the Prince Edward Island Marathon 2:23 faster than his qualifying time for Boston.

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“I didn’t think I read the message right,” MacKenzie said of the moment he was notified he was turned down. “I didn’t expect it. I had set my hotel up. I had geared my whole spring for this trip. There was nothing in my mind that said I wouldn’t be going.”

Now he, and a lot of other people, won’t be.

MacKenzie plans to help encourage the seven people from his running club who did make it in. “Instead of feeling sorry for myself, I want to support those new runners who are going down for the first time,” he said. And he’ll “absolutely” keep trying to qualify himself.

Sullivan, too, said he’s “definitely not done with it yet. All you can do is get back out there and hit the pavement again.”

Matalene is “still trying to figure out what to do. I don’t want to give up on a dream I’ve had forever. I think I’m going to keep trying.” She’s considering running the Houston Marathon and improving her time again for Boston.

Scott has already registered for Houston. She has also applied to run Boston in April for a charity.

“I have this pride. I want to make it in on my own. But this year, I’m like, I did make it in,” she said.

If she does run for charity, Scott said, she knows she has another challenge ahead of her: raising all the money that requires.

“One second,” she said, “is costing me, like, $5,000.”