Mary began riding when she was big enough to sit in the saddle. She and her mother broke horses on their Colorado ranch, while her father ran a mercantile in town. She began riding in local rodeos, soon leaving the ranch to begin a career as a celebrated saddle bronc rider. She married Bill Parks and crisscrossed the continent, competing in rodeos in every state, Mexico, Canada and Cuba. “Retiring” in 1948, Mary continued to ride in quadrilles and barrel race.