Boston Marathon has officially retired the number 261 in honour of Switzer.
Geoffrey Kirui and Edna Kiplagat led a Kenyan clean sweep at the 121st Boston Marathon on Monday, both timing late bursts to perfection to claim the men's and women's races of the prestigious event.
Having registered inconspicuously using her initials "K. V. Switzer", the 20-year-old entered the race sporting lipstick, eyeliner and all trappings of "femininity" under the number "261".
Fifty years on, aged 70, Ms Switzer returned to the starting line wearing the same number.
Women were allowed to participate in the Boston Marathon from 1972. In the past, the nine-year-veteran has run the Boston, Chicago, Detroit and NY marathons using a hand-bike, according to WCVB.
Before the race, she wrote on Facebook: "Today is the race of my life".
"It was a race of celebration, and all along people were cheering me", she told CBS Boston. "If all of this happened in 50 years, imagine what is going to happen in the next 50 years".
Crossing the finish line on Boylston Street was really inspiring.
"He said, 'No dame ever ran no marathon, '" she said.
Switzer's coach in 1967 was a 15-time Boston Marathoner and didn't think a woman could do it - which energized Switzer to try.
Meanwhile, Kathrine went on to complete 39 marathons, and win the New York City marathon in 1974, before creating a series of women-only races (the Avon International Running Circuit) across the world.
Of her legacy, Switzer said it came as no surprise that women continued to embrace the "sense of empowerment" that came from running.
"It was a very good thing she wasn't well-behaved on that morning", said Joann Flaminio, the first female president in the 125-year history of the B.A.A.
Sumgong's former training partner, the 2014 Chicago and Boston Marathon champion Rita Jeptoo, is serving a four-year ban after also testing positive for EPO.