Fifty years ago, a runner officially entered as K.V. Switzer participated in the Boston Marathon. On Monday morning, she did it again at age 70.

Kathrine Switzer’s marathon in 1967 became historic because she was the first woman to complete the all-male race as an official entrant — her registration as “K.V. Switzer” hid her gender. The race resonated far beyond a footnote in the record books when an official tried to force her from the course after a few miles.

“The marathon was a man’s race in those days; women were considered too fragile to run it,” she wrote in an essay for The New York Times 10 years ago. “But I had trained hard and was confident of my strength. Still, it took a body block from my boyfriend to knock the official off the course.” Switzer recovered to finish in 4 hours 20 minutes.

Switzer completed this year’s race only a little slower, in 4:44:31.

Women were finally officially allowed to enter the Boston Marathon in 1972.

Women’s marathoning has come a long way, joining the Olympics in 1984 and gaining popularity through runners like Grete Waitz and Tegla Loroupe. More than half of marathon runners in the United States are women.

“In 1967, few would have believed that marathon running would someday attract millions of women, become a glamour event in the Olympics and on the streets of major cities, help transform views of women’s physical ability and help redefine their economic roles in traditional cultures,” Switzer wrote.

Over the years, Switzer has competed in more than 30 marathons, winning New York in 1974 in 3:07:29, and has worked as a television commentator. She is the founder of 261 Fearless, a running club for women. The name comes from the number she wore in 1967. Switzer started this year’s marathon on Monday morning wearing the same number. It will be retired after the race. Before her start at 11:15 a.m., she was given the honour of firing the gun for the women’s elite runners.

“I’m so excited about Monday. It’s going to be great,” she told NESN. She has said she hopes to run New York this year as well.

Switzer completed the first 30 kilometres of the race in 3:20:18, on pace for about a 4:41 marathon.

Of her legacy as a pioneer, she wrote in The Times: “We learned that women are not deficient in endurance and stamina, and that running requires no fancy facilities or equipment. Women’s marathoning has created a global legacy.”