Who was the first woman to run the Boston Marathon unofficially?

Bobbi Gibb was the first woman to run the Boston Marathon unofficially.

Gibb completed the 1966 Boston Marathon after race officials had told her that women were not eligible to enter. She hid near the start, joined the field after the race began, and finished in about three hours and 21 minutes. Her participation challenged the belief that women could not safely complete a marathon.

Kathrine Switzer entered the 1967 Boston Marathon with an official race number, making her the first woman to run it as an officially registered competitor. The two stories are therefore related but not interchangeable.

Women’s marathon participation later became formally recognized, and the event helped build momentum for women’s distance running. The women’s marathon was added to the Olympic program in 1984.