McGee was born in Juneau, Alaska on December 12, 1936. She then moved to Iowa to live with her grandparents during World War II as Alaska was considered to be at risk of a Japanese invasion. In 1944 the family settled in Phoenix, Arizona.
McGee raced a variety of cars, including the 550 Porsche Spyder
McGee began racing sports cars with the Sports Car Club of America in December 1957,driving a Mercedes 300SL owned by George Rice of Phoenix Arizona. She consistently won her races, which earned her media attention.
A January 1962 article in Motor Trend started with "Housewives revolt!" and ended with "so ladies if you are bored with freeway traffic, don’t give up. Buy a motorcycle and join Mary McGee." She continued racing sports cars until the summer of 1964.
In 1966 McGee purchased a 250cc CZ and raced it through 1967 when she started racing Husqvarna. In 1967 Mary started racing Baja events. McGee’s career highlight racing bikes in Baja was in 1975, when she rode a 250 Husqvarna solo in the Baja 500, passing 17 two-man teams. McGee says that the hardest thing she ever did was Baja. "It was very barren, no electricity, no doctors, no phone. I carried Percodan in case of injury because you’d have to ride injured to get to someplace where someone has a car to get to Ensenada or La Paz to a clinic or back to the States.
Luckily, I never had to use the Percodan, but I did come off the bike several times.McGee ended her motocross and long distance dirt racing around 1976 for several years. In 2000 after moving to Northern Nevada and meeting old motorcycle friends, she bought a 1974 250cc Husqvarna and started entering the women’s class in vintage motocross events. McGee started off in the over 60 class then moved on to the over 70 class a few years later.
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