[1][Note 1] Originally from St. Louis, Missouri, McCormick became enthralled with bullfighting after a trip to Mexico City with her family at the age of seven.

The McCormick family eventually moved to Big Spring, Texas, where her father became chief engineer at Cosden Petroleum.

She studied art and music at Texas Western College in El Paso and rediscovered bullfighting in the neighboring Mexican city of Ciudad Juárez.

[1] She joined the Matador's Union soon after and began bullfighting as a professional Matadora in January 1952, the first American to do so.

Six times bulls gored her, once so seriously in September 1954 in Ciudad Acuña that a priest administered last rites.