DAA Industry Opt Out, determined to emerge as the world's first man to run under 4 minutes in the mile. In charging to the finish line in 3:59.4, Bannister broke a threshold many considered unattainable, a mythical, magical mark in track-and-field lore.

Sixty years after Bannister's feat, much has changed.

Bannister's world record has been toppled 18 times, most recently by Hicham Eluerrouj, who ran 3:43.13 in 1999. Meanwhile, more than 400 American runners have broken the 4-minute barrier; 23 new U.S. athletes were added to the ranks just last year.

And yet, 60 years after Bannister's feat, nothing has changed.

While no longer the headline-grabbing performance of Bannister's day, the sub-4-minute mile still matters. It remains one of the most lauded achievements in the running universe, a standard as recognized by laymen as by track-and-field aficionados, a mark etched in the American consciousness as a feat of athletic grandeur.

"When you're developing as a young athlete, you dream of what you can do, and 4 minutes was one of those dreams for me," says elite agent Ray Flynn, who collected 89 sub-4:00 miles during his running career.

Other runners who have chased the mark reflect a mixture of perspectives. For some, it was a glorious mission, whether they achieved the standard or not; for others, the barrier was passed while on an adventure elsewhere. The moment, however, never flees; it's recalled with detail and enthusiasm.

Few will ever know such a renowned triumph, but the quest to achieve a difficult time goal is familiar throughout the ranks of runners. Success delivers a flood of satisfaction, relief in living up to your expectations, a hunger for more, a humbling sense of perspective within the accomplishment. Failure hurts, but often leaves an appreciation for the journey.

Those who have toyed with the sub-4:00 feat are no different. Their journeys are travels of pride and perseverance, lessons learned and memories made.

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MARCUS O'SULLIVAN

Ireland native Marcus O'Sullivan ran 101 sub-4:00 miles, the first of which came during his junior year at Villanova University. A coach at his alma mater for the past 16 years, O'Sullivan has now watched 12 of his runners accomplish the feat.

"There are two things I remember about the first time I ran sub-4:00. The first was having to run right to the bathroom after the race to throw up. The second came about 10 years later when I was cleaning out my basement on a rainy day and saw the trophy from that race. At the time, I was 33 years old and looking for an exit plan to retire. Seeing that trophy got me nostalgic. I had kept diaries for years and began counting the sub-4:00 miles I had run. At that point it was about 60. I went from thinking I'd retire to deciding I would make a run at 100 sub-4:00 miles.

"Over the next five years, I took every opportunity I could to run the mile. My 100th time came in Madison Square Garden at the Millrose Games. Then I ran another one in Australia just for good measure. That pursuit energized me."

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DON BOWDEN

On June 1, 1957, Don Bowden made history as the first American to break 4:00 in the mile when he ran 3:58.7 in Stockton, Calif. For Bowden, it was his first--and only--time running asub-4:00 mile.

"As a kid at Lincoln High in San Jose, I remember hearing about Bannister's sub-4:00 mile in 1954. For a long time, people thought sub-4:00 was something to be feared. No one knew what was on the other side. When Bannister didn't collapse and die at the finish line, he showed it could be done.

"Being a half-miler, the mile wasn't really on my radar, but after I didn't perform up to my capabilities at the 1956 Olympics in Melbourne, I started looking for a new goal. The 4-minute mile was just what I needed.

"When I ran under 4 minutes that day in Stockton, it was a big relief, but what I remember most about that was a special feeling I'll never forget."

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All About 75 Hard

For more than a decade, Marcus Dunbar attempted to become the first Alaskan to run sub-4:00, coming as close as 4:00.58 in 1993. In 2013, Dunbar's son, University of Oregon track standout Trevor Dunbar [pictured at right], accomplished the feat, running 3:59.06.

Marcus: "The sub-4:00 mile was something I always wanted to accomplish, and it was painstaking not to be on that list when the achievement seemed so close and so possible. To some extent, I think Trevor was motivated to get it done because he understood my history.

"When Trevor made his run at [the sub-4:00 mile], he wore my old Team Alaska Track Club singlet, and the race was at Roosevelt High, a place where I used to do workouts while at the University of Portland [in Oregon]. When he crossed that line under 4 minutes, I won't say I cried, but I definitely wore a big smile on my face for days. That was about the best consolation prize one could imagine."

Trevor: "Growing up, I knew my dad was still a really good runner, so I took an interest in what he was doing. When I got to high school, he was my coach, too. Once I started to have success in high school, I wanted to have more and to continue training hard. The sub-4:00 mile was a huge goal of mine, something every runner strives for once they think it is a possiblity, and my dad trying to do it gave it added symbolism for me.

"I had been injured almost all of the winter and was really fresh, looking for meets. Portland had a meet with a mile on July 15.

"My dad had bought a new car in the States, and he wanted to drive it up [to Alaska] with me, through Canada. He had to switch his plane ticket a few days earlier to make it to the meet. He said it was definitely worth it.

"Whenever my dad watches races, he's got the coach's mentality, so he's got a stopwatch and he's always taking splits. He was right there at the finish line every 440, reading off the splits.

"After the meet, I did the drive for the first time with my dad. It was cool. We were joking around that the trip would have been a lot longer had I run a second slower."

DATHAN RITZENHEIN

Despite being one of America's most accomplished distance runners, Dathan Ritzenhein is absent from the sub-4:00 list. He has, however, run under 13 minutes for the 5K and 2:07 for the marathon, far more exclusive distance-running clubs.

"I have actually never made a run at a sub-4:00 mile. I tried it in practice before, thinking I could do it, but never went to a race with that explicit goal. Sub-4:00 was relevant, but it always took a back seat to other goals, and I can't say I'd trade those achievements for a sub-4:00 race.

"But now that [running sub-4:00] is getting further and further away from me, I'll admit there's some disappointment in that. The 4-minute mile is something that every distance runner thinks of as one of the sport's great milestones."

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TOM O'HARA

Tom O'Hara dipped under the 4-minute barrier in 1963 while a junior at Loyola University in Chicago. The following year he set the world record in the indoor mile when he clocked 3:56.4.

"That first time I broke 4 minutes, I wasn't particularly overjoyed because I actually finished second in the race to Jim Beatty. My goal was to win the race, so breaking 4 minutes was secondary. It wasn't until much later that I realized the relevance and significance of the 4-minute mile, as people wanted to hear about it. That makes the achievement quite humbling."

NATHAN ROBISON

In Seattle on Valentine's Day 2004, Brigham Young University's Nathan Robison became the 259th American to break the 4-minute mile when he clocked a 3:59.99. That mark inspired Robison's college teammates to label him "the world's slowest sub-4:00 miler."

"It's funny how I remember that date but none of the others.

"When we were driving to the track, I had my headphones on, listening to music and focusing on my race as I looked out the window. It was a cold, rainy day, and we passed under an overpass where a bearded, long-haired man stood completely naked, facing the traffic. We all thought it was hilarious and, in our team lore, that became a good omen for a PR.

"The race was fairly steady. From the beginning, I had hoped to split 59s and then finish as fast as I could. While the first quarter was 58 or 59, I slowed to 60 and 61 on the next two, and I knew running sub-4:00 would be close.

"I led most of the race and remember thinking that the pace never felt easy. In practice I had focused on running quarters, 10 to 12 of them at 58 or 59, to understand the sub-4:00 pace, and they felt easy then. In this race, though, there was never a moment when I felt comfortable. It was a race against the clock, and it never relented. It felt mechanical and calculating; it was all about time rather than dueling it out with other living racers.

"[After I finished], my coach and my dad had both hand-timed me under 4:00, but we all waited impatiently for the official announcement. I stepped off the track as the announcer began the results, and it was a strange mix of emotions when I heard I officially broke 4:00, especially by just one one-hundredth of a second. I felt physically beat-up, but it was pure elation knowing that I had put my body through a barrier people had once thought impossible.

"There was this massive sense of relief and pride throughout the rest of the day and evening, though I felt physically and emotionally drained. About 2 a.m. I went to the hotel lobby for cough medicine, and an employee offered to drive me to a local gas station. In the car, we chatted about running and about my race. That conversation was the first time everything came into perspective. It was marvelous to feel so utterly exhausted by my performance, but also a little scary to understand the physical and emotional cost of that race."

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ZACH DAHLEEN

In February, Zach Dahleen was preparing for his final track season at Southern Illinois University and another assault on the sub-4:00 barrier following two narrow misses--4:00.16 and 4:00.46--in his previous two collegiate seasons.

"Ever since high school, I believed this was a possibility, and it's been my goal for the last five years. When I was .16 off two years ago, I'll admit I was bitter. I thought about all the things I could've done better. I'd like to say 4 minutes is an arbitrary number that doesn't mean much, but deep down I know it's more significant than that. It's the standard in track . . . a primary goal I want to achieve."

STEVE SCOTT

During his junior year at the University of California-Irvine in 1977, Steve Scott broke 4:00 in the mile for the first time. Over the next 16 years, Scott would earn the American mile record (3:47.69) and accumulate 136 sub-4:00 miles, more than anyone in the world.

"There had never been a sub-4:00 mile in the history of the Drake Relays, and the organizers there invited me out in 1978, my senior year in college, to chase it. In the days leading up to that race, I had a 102-degree temperature, but I still traveled from California to Iowa hoping to race. When I wasn't able to run, the organizers asked if I'd address the crowd. I apologized for not being able to run and guaranteed I'd come back the following year to break 4:00.

"When I returned to Drake in 1979 to uphold my promise, the weather was horrible: 15 mile-per-hour winds and damp conditions. The people in the stands, though, knew the story, and they came to see me break 4:00. When I came through 1200 meters right at 3:00, the crowd went crazy. That encouragement carried me through, and I ran under 4:00. Everywhere I went in town that day, people treated me like the president. That showed me what the sub-4:00 mile meant to others.

"As my career progressed, I actually felt disappointed in races where I didn't break 4:00. It became so expected--by me and others. I felt a responsibility to the crowd, to perform for them and give them something they might never see again."

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LEN SITKO

After running 4:00.56 in the mile in 1991 and feeling that he had "topped out," Len Sitko continued to chase the sub-4:00 barrier during his final year at the University of Illinois. In 1992 Sitko ventured to Birmingham, England, where he ran 3:59.29 and recorded his career's only sub-4:00 performance.

"That race in Birmingham was actually a bad one for me, and I remember being bummed on the flight back to the U.S. The fact that I had finally broken 4 minutes was so secondary because I felt I hadn't fully capitalized on the opportunity that race presented.

"To be honest, it took me years to see that accomplishment through a different lens. Now, when something good happens in life, I try to enjoy that, to appreciate things in a way I didn't then.

"I'm 45 now and people still introduce me as a 4-minute miler. It's embarrassing, but also humbling to know that I'm a part of this club that others recognize as something rare and special."

GREG CARLBERG

Greg Carlberg, now B5, dipped under the 4-minute threshold during his senior year at the University of Nebraska, running 3:59.6 at the Houston Astrodome on Feb. 13, 1971. It would be the only sub-4:00 race of his career.

"That race might be more than 40 years old, but it's still fresh in my mind. I had run 4:02 the year prior and was coming off an All-American cross country season. I knew I was in good shape and had a chance to run under 4:00. Once you realized you were a good miler, then 4 minutes became the goal you chased.

"The race in Houston was on a quick, oversize track and had [U.S. miler] Marty Liquori and [future Olympian] Len Hilton, so I knew things were in place for me to run fast. From the get-go I tracked Liquori and Hilton, and by the half it was a three-man race. I remember hitting the three-quarter mark in 3:03, so obviously I was going to have to hammer the last quarter. I knew getting under 4:00 would be tight, but I didn't doubt it was possible, especially knowing that endurance was my strong suit.

"Over that last lap, I don't know if Liquori and Hilton were trying to get away from me, but I know I was chasing them. I just kept digging and digging--around the turn and onto the straightaway--but couldn't make up any ground on them. Liquori won rather handily, and I was able to hang on for third. The results flashed on the scoreboard almost immediately, and I saw that I broke 4:00. I'll admit, I was pretty ecstatic.

"Later that night, I and a quarter-miler buddy of mine who was also of legal age went to a disco in Houston, which was foreign to someone like me from Nebraska. I always remember that day because it was one of firsts: my first, and actually only, sub-4:00 mile and my first time seeing a disco. Hard to forget either of those experiences."

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KURT MICHAELIS

A 2003 NCAA All-American in the indoor mile, Kurt Michaelis holds a personal best of 4:02.7. The Youngstown State alum describes the sub-4:00 mile as "the albatross that still hangs around my neck."

"My first aspirations of running sub-4:00 came when I was a high school freshman and I ran 4:23 for the 1600. My coach handed mean article on [California prep star] Michael Stember chasing the 4-minute mile, and I became fascinated. I never had any visions of winning Olympic gold, but I looked at sub-4:00 as something I could do.

"Truthfully, I thought it would be easier than it actually was. I ended up running 4:15 [for the 1600] in high school on about 25 miles a week. I thought I'd get great college training and my times would drop, but it wasn't until my junior year that I broke 4:10.1 still thought 4:00 was within reach, though, and when I ran 4:02 [in my fourth year], that race was set up for me to run sub-4:00.1 just didn't get it done.

"For a good few years after I graduated, I kept thinking about getting myself back into shape so I could make a run at it. Was that even possible? I just couldn't let it go. After about six years, I got over it and accepted reality.

"Running a 3:59.9 wouldn't have changed my life--I know that--but it sure would be nice to tell my kids I did it and to look at a list of those who've done it and see my name alongside the greats."