Last year, 45 percent of Boston Marathon runners were women. 

50 years ago, there was one. 

Until 1972, women weren’t allowed to compete in the Boston Marathon. Bobbi Gibb was the first woman to finish the race, sneaking on to the course in 1966. This year marks the 50th anniversary of the historic occasion.

"I think I started running the minute I could walk," says Gibb. "I just never stopped running, and all my little girlfriends stopped running when they got to be, I don't know, 13, 14, 15 years old. And I was still running in the woods with the neighborhood dogs. And I was 20 years old and I was still running. I just love to run-- because somehow, it made me feel more alive."

I just love to run-- because somehow, it made me feel more alive.

In the 1960's, a woman's role in American society was still mainly to support her husband, the breadwinner. But Gibb wanted something different.

"I felt there was something really basic missing in the kind of suburban life that was set out for us, especially for women. I think I was looking for something deeper," says Gibb.

Gibb watched the Boston Marathon in 1964 with her father. It was the first time she had ever seen other people running, and the sight had a real effect on Gibb.

"I saw all these people running by, and I wasn't thinking whether they were men or women-- I just saw these incredibly strong, enduring people. And to me, it said something very deep about what it is to be human," says Gibb.

"It's as primal as when we stood up on the central plains of Africa, and stood up on our hind feet and started to run. There's something so basically human about that kind of endurance. The courage it takes to run a race like that, and to live a life of integrity-- I just fell in love with it."

There's something so basically human about that kind of endurance.

Gibb started training the next day. Many miles later, she was ready. Living in California at the time, she wrote in her application for the Boston Marathon. But the race director of the Boston Athletic Association, Will Cloney, wrote back to tell Gibb that women were not physiologically able to run a marathon, and the BAA couldn't take the medical liability. Furthermore, women weren't allowed to race more than a mile and a half competitively.

"At the time, I was running 40 miles at a stretch," says Gibb. "So I read this thing, 'Women can't run more than a mile and a half,' and I say 'Ok, they have something to learn.'"

"But I also saw that, if I could overturn this false belief about women, I could throw into question all the other false beliefs about women that had been used to keep women in virtual subjugation for centuries."

But I also saw that, if I could overturn this false belief about women, I could throw into question all the other false beliefs about women that had been used to keep women in virtual subjugation for centuries.

It was at that point that Gibb realized her run was going to be a social statement.

"Here's the whole tragedy of prejudice: if you're not allowed to do something, how can you ever prove you can do it?" Asks Gibb. 

Gibb took a Greyhound bus back to Boston for the race. When she arrived, she called her parents and told her where she was, and what she planned on doing. "They totally freaked out. My father thought I was delusional," says Gibb.

But Gibb convinced her mother that by running the Boston Marathon, she was accomplishing something important for all woman. "I said Mom, this is going to help to set women free. That struck a bell with her, I mean tears came to her eyes," says Gibb.

Her mother said she would drive Gibb to the start of the race in Hopkinton. "It was the first time she had ever been on my side in my battle against this. So she drove me to the start, and we hugged for the first time in years," says Gibb.

On April 19, 1966 Gibb stood at the start of the Boston Marathon. She was wearing a black bathing suit, her brother's Bermuda shorts, and a hooded-sweatshirt with the hood pulled up to hide her hair and face. Gibb didn't know what was going to happen, but she figured there was a chance she could be arrested; after all, she was doing something illegal. Gibb hid in a clump of bushes next to the starting line-- when the gun went off, and half the pack ran by, she jumped into the race.

It didn't take long for the other runners to notice there was something different about Gibb. 

"I could hear the guys behind me...'Is that a girl, is that a girl?'" Says Gibb.

It took Gibb's fellow runners about three minutes to figure out she was, in fact, a girl. That might have been the end of Gibb's marathon attempt, but instead the racers voiced their support. "They could've easily shouldered me out of the race, but instead they said 'I wish my girlfriend would run, I wish my wife would run.'"

When Gibb told them she was afraid she would be kicked out of the race, the men said they "won't let them throw you out".

But Gibb's fellow runners weren't the only ones who noticed. Soon, the press started to notice that there was a woman running in the race. A local radio station started to broadcast her progress. By the time Gibb got to Wellesley College, the women were looking for her. 

One of the Wellesley students that day was Diana Chapman Walsh, who would later become president of the college. Walsh remembers looking for Gibb in the race:

"The word spread to all of us lining the route that a woman was running the course. We scanned face after face in breathless anticipation until a ripple of recognition shot through the lines and we cheered as we never had before. We let out a roar that day, sensing that this woman had done more than just break the gender barrier in a famous race."

Gibb finished the race that day in 3:21:40, ahead of two-thirds of the pack. The governor of Massachusetts came down to shake her hand, and the next day her feat made the front page of the news.

Fifty years later, Gibb still runs an hour or two a day. She's also working on getting a sculpture of a woman runner on the marathon route. Right now, the sculptures are all of men.

"When you're trying to create something new, you don't know what it is yet, you haven't created it yet," says Gibb.

But Gibb's already broken the mold once.