History
The first woman known to have finished the Boston Marathon was Roberta Gibb, in 1966. Gibb was not officially entered. She had sent in an entry form, but it was returned to her with a note saying that she would not be allowed to enter because a woman wasn't physically capable of running a marathon.
Gibb set out to prove that idea wrong. She hid behind a bush near the start, made her way into the field without being observed, and finished in the unofficial time of 3:21.25.
In 1967, the BAA accepted an entry form from K. V. Switzer of Syracuse University. About two miles into the race, officials realized that Switzer was a woman. They tried to get to her to pull her off the course, but she was protected by male friends from Syracuse. The officials eventually gave up and Switzer finished the race in an unofficial 4:20.
Gibb also sneaked into the 1967 run, as she had the year before, but she was discovered and taken from the course shortly before the finish.
Photographs of the race officials trying to catch Switzer ran in newspapers nationwide the following day, focusing attention on the growing debate about whether women should be allowed to run in long-distance races.
The debate went on for several more years. The BAA didn't formally allow women to enter the Boston Marathon until 1972, but officials stopped trying to keep them out of the race.
In fact, the top women finishers from 1966 through 1971 are now listed as unofficial winners: Gibb from 1966 through 1968 and Sara Mae Berman from 1969 through 1971.